Medical Dictionary

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

clump (klump)
To form into clusters, small aggregations, or groups. [A.S. clympre, a lump]

clumping (klump-ing)
The massing together of bacteria or other cells suspended in a fluid.

cluneal (kloo′ne-al)
Pertaining to the clunes.

clunes (kloo′nez)
buttocks. [pl. of L. clunis, buttock]

clupanodonic acid (kloo-pan′o-don′ik)
An ω-3 fatty acid with 22 carbons and five double bonds; found in fish oils and phospholipids in brain.

cluster of differentiation
Cell membrane molecules that are used to classify leukocytes into subsets. CD molecules are classified by monoclonal antibodies. There are four general types: type I transmembrane proteins have their COOH-termini in the cytoplasm and their NH2-termini outside the cell; type II transmembrane proteins have their NH2-termini in the cytoplasm and their COOH-termini outside the cell; type III transmembrane proteins cross the plasma membrane more than once and hence may form transmembrane channels; and glycosylphosphatidylinositol-anchored proteins (type IV), which are tethered to the lipid bilayer via a glycosylphosphatidylinositol anchor. CD1a a type I transmembrane protein found on thymocytes, Langerhans cell, brain astrocytes, and dermal cells that is involved in nonclassical antigen presentation or is a receptor for an undefined ligand or hormone; expressed in patients with T-cell acute lymphoblastic leukemia, histiocytosis X, and thymomas. CD1b a type I transmembrane protein found on cortical thymocytes, dermal cells, and brain astrocytes that is involved in nonclassical antigen presentation or is a receptor for an undefined ligand or hormone; expressed in patients with T-cell acute lymphoblastic leukemia, T-cell lymphoma, and thymomas. CD1c a type I transmembrane protein found on cortical thymocytes, dermal cells, and brain astrocytes that is involved in nonclassical antigen presentation or is a receptor for an undefined ligand or hormone; expressed in patients with T-cell acute lymphoblastic leukemia, B-cell chronic lymphocytic leukemias, and B cells in severe combined immunodeficiency disease. CD2 a type I transmembrane protein found on thymocytes, T cells, and some natural killer cells that acts as a ligand for CD58 and CD59 and is involved in signal transduction and cell adhesion; expressed in T-cell acute lymphoblastic leukemia and T-cell lymphoma. CD2r a type I transmembrane protein found on T cells and some natural killer cells that is unrelated to binding sites for CD58 and CD59; expressed on activated T cells in autoimmune diseases. CD3 a type I transmembrane protein found on T cells that forms the signal transduction unit for the T cell; expressed in patients with T-cell lymphomas. CD4 a type I transmembrane protein found on helper/inducer T cells, monocytes, macrophages, and dendritic cells that is involved in T-cell recognition of antigens; expressed in mycosis fungoides, Sézary syndrome, and T-cell lymphomas. CD5 a type I transmembrane protein found on T cells, thymocytes, and some B cells that is a ligand for CD72 and is involved in cellular activation or adhesion; expressed in B-cell chronic lymphocytic leukemia and T-cell lymphoma. CD6 a type I transmembrane protein found on T cells, medullary thymocytes, some cortical thymocytes, a few B cells, and in brain. CD6 is phosphorylated on cellular activation and possibly plays a role in signal transduction; expressed in some B-cell chronic lymphocytic leukemias. CD7 a type I transmembrane protein found on thymocytes, some T cells, monocytes, natural killer cells, and hemopoietic stem cells; expressed in patients with mycosis fungoides, some patients with T-cell acute lymphoblastic lymphoma, and a few patients with acute nonlymphocytic lymphoma. CD8 a type I transmembrane protein found on suppressor (cytotoxic) T cells, some natural killer cells, and most thymocytes that is involved in T-cell antigen recognition; expressed in some T-cell lymphomas and large granular lymphocyte leukemias. CD9 a type III transmembrane protein found on platelets, megakaryocytes, monocytes, pre-B cells, eosinophils, basophils, and activated T cells; plays a role in signal transduction leading to platelet activation and aggregation; expressed in some T-cell acute lymphocytic leukemias and some acute nonlymphocytic leukemias. CD10 a type II transmembrane protein found on pre-B cells, germinal-center B cells, some neutrophils, kidney cells, T-cell precursors, and epithelial cells that acts as a zinc metalloprotease cleaving peptide bonds on the amino side of hydrophobic amino acids; expressed in acute lymphocytic leukemia and follicular-center–cell lymphomas. CD11a a type I transmembrane protein found on lymphocytes, neutrophils, monocytes, and macrophages that facilitates cell adhesion and cell activation; expressed in lymphomas. CD11b a type I transmembrane protein found on monocytes, macrophages, granulocytes, some B cells, dendritic cells, and natural killer cells that facilitates cell adhesion, phagocytosis, and/or chemotaxis; expressed in some B-cell chronic lymphocytic leukemias, most acute nonlymphocytic leukemias, and some hairy cell leukemias. CD11c a type I transmembrane protein found on monocytes, macrophages, neutrophils, and some B cells that induces cellular activation and helps trigger neutrophil respiratory burst; expressed in hairy cell leukemias, acute nonlymphocytic leukemias, and some B-cell chronic lymphocytic leukemias. CDw12 a membrane protein found on monocytes, neutrophils, and platelets; the function of this moiety is unknown. CD13 a type II transmembrane protein found on myeloid cells that acts as a zinc-binding metalloprotease catalyzing removal of NH2-terminal amino acids from peptides; expressed in some types of acute nonlymphocytic leukemia. CD14 a transmembrane protein found on monocytes, macrophages, neutrophils, some B cells, and dendritic cells that is involved in signal transduction leading to oxidative burst and/or synthesis of tumor necrosis factor-α; expressed in some patients with acute nonlymphocytic leukemia and in B-cell chronic lymphocytic leukemia. CD15 a phosphatidylinositol-anchored transmembrane protein found on neutrophils and which may be involved in phagocytosis; expressed in patients with Hodgkin disease, some B-cell chronic lymphocytic leukemias, acute lymphoblastic leukemias, and most acute nonlymphocytic leukemias. CD15s a transmembrane protein found on neutrophils, monocytes, myeloid cells, and some T cells that serves as the major ligand for CD62E; expressed on squamous cell carcinomas. CD16 a type I transmembrane protein found on natural killer cells and macrophages that is involved in directing NK cell activation. CD16b a glycosylphosphatidylinositol-anchored protein present on neutrophils; deficient in patients with paroxysmal nocturnal hemoglobinemia and expressed in large granular lymphocytic leukemias and natural killer cell leukemias. CDw17 a type I transmembrane protein found on monocytes, neutrophils, and platelets that may play a role in granule content packaging or exocytosis. CD18 a type I transmembrane protein found on lymphocytes, neutrophils, monocytes, macrophages, some B cells, dendritic cells, and natural killer cells that appears active in signal transduction; expressed in some patients with B-cell chronic lymphocytic leukemia, most acute nonlymphocytic leukemia, and some hairy cell leukemia. CD19 a type I transmembrane protein found on all B cells and B-cell precursors and some follicular dendritic cells that acts as an accessory molecule for B cell signal transduction; expressed in all B-cell neoplasms. CD20 a type III transmembrane protein found on B cells that forms a calcium channel in the cell wall allowing for the influx of calcium required for cell activation; expressed in B-cell lymphomas, hairy cell leukemia, and B-cell chronic lymphocytic leukemia. CD21 a type I transmembrane protein found on B cells, follicular dendritic cells, pharyngeal and cervical epithelial cells, some thymocytes, and some T cells that plays a role in signal transduction; expressed in hairy cell leukemia, B-cell lymphoma, and some T-cell acute lymphocytic leukemias. CD22 a type I transmembrane protein found in the cytoplasm of pre-B cells and on the surface of mature B cells that facilitates signal transduction; expressed in patients with hairy cell leukemias and in some with B-cell lymphomas. CD22α a type I transmembrane protein found on mature B cells that facilitates adhesion of B cells to monocytes and red blood cells. CD22β a type I transmembrane protein found on mature B cells that facilitates adhesion of B cells to CD4-positive T cells. CD23 a type II transmembrane protein found on mature B cells, monocytes, activated macrophages, eosinophils, platelets, and dendritic cells that enhances capture and processing of antigen complexed with IgE. CD24 a glycosylphosphatidylinositol-anchored protein present on B cells, pre-B cells, neutrophils, and a few thymocytes that may play a role in inducing B-cell proliferation and differentiation; expressed in patients with B-cell lymphomas and some with B-cell chronic lymphocytic leukemias. CD25 a type I transmembrane protein present on activated T cells, activated B cells, some thymocytes, myeloid precursors, and oligodendrocytes that associates with CD122 to form a heterodimer that can act as a high-affinity receptor for IL-2; expressed in most B-cell neoplasms, some acute nonlymphocytic leukemias, and neuroblastomas. CD26 a type II transmembrane protein present on mature T cells, some B cells, apical membranes of epithelial and endothelial cells, kidney, intestinal brush borders, and liver bile canaliculi that combines with collagen and associates with adenosine deaminase. CD27 a type I transmembrane protein present on mature T cells, medullary thymocytes, and some B cells that is a ligand for CD70 and serves as a member of the nerve growth factor family; expressed in chronic lymphocytic leukemia. CD28 a type I transmembrane protein present on most CD4 T cells, many CD8 T cells, and most plasma cells that enhances the transcription and stability of IL-2 messenger RNA. CD29 a type I transmembrane protein present on some CD4 helper T cells, platelets, and dendritic cells that is involved in cell-cell or cell-matrix adhesion. CD30 a type I transmembrane protein present on activated T and B cells that may play a role in cell activation and/or differentiation; expressed in Hodgkin disease, some T-cell lymphomas, and anaplastic large cell lymphomas. CD30l a type III transmembrane protein present on activated T cells and monocytes that can induce differential responses in CD30-expressing cells ranging from growth to cell death. CD31 a type I transmembrane protein present on myeloid cells, platelets, endothelial cells, natural killer cells, monocytes, and subsets of CD4-positive T cells that acts as a cosignal transducer for macrophages, inducing respiratory burst; plays a key role in the transmigration of leukocytes through intercellular junctions of vascular endothelium and mediates calcium-dependent heterophilic aggregation; expressed in neoplastic endothelial cells. CD32 a type I transmembrane protein present on monocytes, B cells, neutrophils, placental trophoblasts, and endothelium; acts as a signal transducer for IgG-mediated phagocytosis and neutrophil and monocyte oxidative burst; transduces an inhibitory signal on B cells and may play a role in placental IgG transport. CD33 a type I transmembrane protein present on myeloid cells and myeloid precursors; expressed in many acute nonlymphoblastic leukemias and some B-cell chronic lymphocytic leukemias. CD34 a type I transmembrane protein present on myeloid cells and myeloid precursors that plays a role in signal transduction; expressed in some acute nonlymphocytic leukemias and some acute lymphocytic leukemias. CD35 a type I transmembrane protein present on monocytes, granulocytes, dendritic cells, red blood cells, some T cells, and glomerular podocytes that facilitates phagocytosis and/or binding of immune complexes; expressed in Wilms tumor. CD36 a transmembrane protein present on monocytes, platelets, megakaryocytes, umbilical vein, small-vessel endothelium, reticulocytes, and mammary epithelium that may be involved in signal transduction; expressed in myeloproliferative disorders. CD37 a type III transmembrane protein present on mature B cells, some T cells, and monocytes that may play a role in ion transport; expressed on B-cell lymphomas, B-cell chronic lymphocytic leukemia, and hairy cell leukemia. CD38 a transmembrane protein present on macrophages, dendritic cells, and activated cells of the natural killer, B- and T-cell lines that can facilitate B-cell adhesion. CD39 a transmembrane protein present on macrophages, dendritic cells, and activated lymphoid cells that facilitates B-cell adhesion. CD40 a type I transmembrane protein present on mature B cells, monocytes, dendritic cells, and epithelial cells involved in signal transduction leading to cell activation, proliferation, adhesion, and/or differentiation; expressed in B-cell chronic lymphocytic leukemias, lymphomas, and some carcinomas. CD40l a type II transmembrane protein present on activated CD4-positive T cells, a few activated CD8-activated T cells, and blood basophils; a ligand for CD40 that induces activation, proliferation, and/or differentiation of CD40-expressing cells. CD41 a type I transmembrane protein present on platelets and megakaryocytes that serves as a receptor for fibrinogen, fibronectin, vitronectin, von Willebrand factor, and other factors and facilitates platelet adhesion and aggregation. CD42 a type I transmembrane protein present on platelets and megakaryocytes that mediates platelet binding to damaged blood vessels. CD43 a type I transmembrane protein present on thymocytes, T cells, granulocytes, monocytes, natural killer cells, platelets, brain, activated B cells, plasma cells, and hemopoietic stem cells that serves as a ligand for CD54 and facilitates cell-cell adhesion; expressed on some myelomas and lymphomas. CD44 a type I transmembrane protein present on T cells, pre-B cells, monocytes, neutrophils, CNS white matter, fibroblasts, skeletal muscle, and medullary thymocytes; facilitates lymphocyte binding to endothelial venules and assists in adhesion. CD45 a type I transmembrane protein present on all hemopoietic cells except erythrocytes that assists in cell activation; expressed in lymphomas, B-cell chronic lymphocytic leukemia, hairy cell leukemia, and acute nonlymphocytic leukemia. CD46 a type I transmembrane protein present on thymocytes, T cells, B cells, natural killer cells, monocytes, neutrophils, platelets, endothelial cells, epithelial cells, fibroblasts, placenta, and sperm that protects against complement-mediated damage. CD47 a transmembrane protein without tissue specificity that is involved in membrane cation flux. CD48 a glycosylphosphatidylinositol-anchored membrane protein present on T cells, B cells, thymocytes, eosinophils, neutrophils, bronchial epithelium, and salivary gland that may play a role in signal transduction on T cells; absent or defective in patients with paroxysmal nocturnal hemoglobinuria. CD49a a type I transmembrane protein present on activated T and B cells, monocytes, neurovascular endothelium, and smooth muscle that forms a receptor for collagen and laminin; expressed on melanomas. CD49b a type I transmembrane protein present on platelets, T cells, B cells, fibroblasts, and endothelial cells involved in platelet adhesion of collagen; may be expressed in melanomas. CD49c a type I transmembrane protein present on B cells, kidney glomerulus, thyroid, and some basement membranes that may play a role in cell-cell adhesion; expressed in most cultured cell lines. CD49d a type I transmembrane protein present on B and T cells, natural killer cells, eosinophils, monocytes, erythroblasts, thymocytes, and myoblasts that facilitates cell-cell adhesion and leukocyte migration and aids in lymphocyte activation; expressed in melanomas. CD49e a type I transmembrane protein present on monocytes, neutrophils, leukocytes, fibroblasts, platelets, and myoblasts that helps form a receptor for fibronectin and activates the sodium-hydrogen antiporter; may serve an accessory role to T-cell activation. CD49f a type I transmembrane protein present on platelets, macrophages, monocytes, thymocytes, T cells, and adherent cell lines that forms a receptor for invasion and laminin; expressed in some acute lymphocytic leukemias. CD50 a type I transmembrane protein present on thymocytes, B cells, monocytes, and neutrophils; involved in intracellular adhesion. CD51 a type I transmembrane protein present on endothelial cells, monocytes, macrophages, platelets, some B cells, osteoclasts, and uterine cells; plays a role in platelet aggregation and/or endothelial cell adhesion and in monocyte migration. CD52 a glycosylphosphatidylinositol-anchored membrane protein present on thymocytes, T cells, B cells, some granulocytes, seminal vesicles, epididymis, and spermatozoa; plays a role in signal transduction. CD53 a type III transmembrane protein present on leukocytes, platelets, osteoblasts, and osteoclasts; contributes to the transduction of CD2-generated signals in T cells and natural killer cells; facilitates cytoplasmic calcium flux in B cells, monocytes, and granulocytes; and plays a role in activation of the monocyte oxidative burst; expressed in hemopoietic neoplasms and myelomas. CD54 a type I transmembrane protein present on leukocytes and endothelial cells and inducible on lymphocytes, dendritic cells, keratinocytes, chondrocytes, fibroblasts, and epithelial cells; acts as a ligand for CD11 and CD18 and aids in intercellular adhesion. CD55 a glycosylphosphatidylinositol-anchored membrane protein present on all hemopoietic cells and spermatozoa that neutralizes complement activation; absent or defective in paroxysmal nocturnal hemoglobinuria. CD57 a membrane protein present on natural killer cells, some T cells, a few B cells, and monocytes of unknown function; expressed in large granular lymphocyte leukemias. CD58 a membrane protein present on many hemopoietic cells and fibroblasts that acts as a ligand for CD2 and may be involved in T-cell function. CD59 a glycosylphosphatidylinositol-anchored membrane protein present on many hemopoietic cells, vascular endothelium, epithelial cells, and placenta that inhibits membrane complement attack and may be involved in T-cell signal transduction; absent or defective in paroxysmal nocturnal hemoglobinuria. CDw60 a membrane protein present on T-cell subsets, some monocytes, and platelets that may play a role in signal transduction leading to cell activation; present on cutaneous T-cell lymphomas. CD61 a membrane protein present on platelets, megakaryocytes, endothelial cells, osteoclasts, and uterine cells that facilitates platelet aggregation and adhesion. CD62e a type I transmembrane protein present on endothelium that facilitates adhesion of neutrophils, monocytes, and some T cells to vascular endothelium; enhanced expression occurs at sites of chronic inflammation. CD62l a type I transmembrane protein present on B cells, T cells, neutrophils, thymocytes, monocytes, eosinophils, erythroid and myeloid progenitor cells, and natural killer cells that functions as a peripheral lymph node homing receptor and facilitates binding to endothelium at inflammatory sites; found on many malignant leukocytes. CD62p a type I transmembrane protein present on activated platelets, endothelial cells, and megakaryocytes that facilitates adhesion of monocytes and neutrophils to activated platelets and to endothelial cells. CD63 a type III transmembrane protein present on activated platelets, monocytes, macrophages, and in secretory granules of vascular endothelial cells and platelet-dense granules; facilitates adhesion to activated endothelium. CD64 a type I transmembrane protein present on monocytes, megakaryocytes, and activated neutrophils that acts as a high-affinity receptor for IgG; present in some cases of acute nonlymphocytic leukemia. CDw65 a membrane protein present on myeloid cells and some monocytic cells that is involved in signal transduction leading to formation of the respiratory burst; present in some acute nonlymphocyte leukemias. CD66a a type I transmembrane protein, present on neutrophils, histiocytes, some myeloid progenitor cells, and the brush border of colonic epithelial cells, that facilitates adhesion and neutrophilic activation; expressed in chronic myelocytic leukemia and some cases of acute lymphocytic leukemia. CD66b a glycosylphosphatidylinositol-anchored membrane protein present on neutrophils that induces aggregation and activation; expressed in chronic myelocytic leukemia. CD66c a glycosylphosphatidylinositol-anchored membrane protein present on neutrophils that induces aggregation and activation; expressed in chronic myelocytic leukemia. CD66d a type I transmembrane protein present on neutrophils that facilitates adhesion and neutrophil activation; expressed in chronic myelocytic leukemia. CD66e a glycosylphosphatidylinositol-anchored membrane protein present in tissues derived from all three germ layers during embryogenesis and adult colon epithelial cells that facilitates calcium-independent adhesion during embryogenesis; expressed in most colon carcinomas and other carcinomas. CD68 a type I transmembrane protein present on monocytes, macrophages, osteoclasts, mast cells, cytoplasmic granules, activated platelets, and large lymphocytes; expressed in neuroma Schwann cells, in nerves undergoing wallerian degeneration, in myeloid cell tumors, and in anaplastic lymphomas and epithelial tumors. CD69 a type II transmembrane protein present on platelets, CD4-positive or CD8-positive thymocytes, activated lymphocytes, and activated T or natural killer cells that functions as a signal transducer, enhancing cell activation and/or platelet aggregation. CD70 a type II transmembrane protein present on activated B cells and some activated T cells that enhances activation of T cells; expressed in Reed-Sternberg cells, some lymphomas, and monocyte lineage–derived tumors. CD71 a type II transmembrane protein present on activated or proliferating cells that facilitates cellular iron uptake; expressed in many acute leukemias and some lymphomas. CD72 a type II transmembrane protein present on all B cells and macrophages that plays a role in signal transduction or adhesion; expressed in B-cell acute lymphoblastic leukemia, B-cell lymphomas, and B-cell chronic lymphocytic leukemia. CD73 a glycosylphosphatidylinositol-anchored membrane protein present on some B cells, some T cells, thymocytes, some epithelial and endothelial cells, and dendritic cells; expressed on most B-cell acute lymphoblastic leukemias, breast carcinomas, and large granular leukocyte leukemias. CD74 a type II transmembrane protein present on B cells, monocytes, dendritic cells, and activated T cells that prevents binding of endogenous peptides; expressed in B-cell chronic lymphocytic leukemia, hairy cell leukemia, and large granular leukocyte lymphomas. CDw75 a type II transmembrane protein present on mature B cells and some T cells that may facilitate B-cell adhesion; expressed in B-cell lymphomas of follicular cell origin. CDw76 a membrane protein present on mature B cells, some T cells, melanocytes, endothelial cells, hepatocytes, and kidney tubular cells; expressed in mature B-cell lymphomas and B-cell chronic lymphocytic leukemias. CD77 a membrane protein present on germinal center B cells, follicular dendritic cells, endothelium, and some epithelial cells which may act as a receptor for toxins of Escherichia coli or Shigella dysenteriae; expressed in Burkitt lymphomas and B-cell lymphomas of follicular center cell origin. CDw78 a membrane protein present on B-cells and tissue macrophages that may be involved in signal transduction; expressed in some acute lymphoblastic leukemias, B-cell lymphomas, and some acute nonlymphocytic leukemias. CD79a a type I transmembrane protein present on B cells that mediates signal transduction; expressed in mature B-cell neoplasms. CD79b a type I transmembrane protein on B cells that mediates signal transduction; expressed in B-cell tumors and B-cell acute leukoblastic leukemias. CD80 a type I transmembrane protein on activated B cells, activated monocytes, activated follicular dendritic cells, and some activated T cells that provide a costimulatory signal to T cells during antigen presentation; expressed in B lymphoblastoid cells. CD81 a type III transmembrane protein present on many cell types, including lymphocytes, that facilitates signal transduction; expressed on lymphomas, leukemias, melanomas, and neuroblastomas. CD82 a type III transmembrane protein present on epithelial cells, endothelium, and activated lymphocytes that may play a role in calcium flux. CD83 a type I transmembrane protein, present on dendritic cells, Langerhans cells, B cells, and interdigitating reticular cells, that may play a role in antigen presentation or the cellular interactions that follow lymphocyte activation. CDw84 a membrane protein present on monocytes, early B cells, platelets, germinal-center B cells, mantle-zone B cells, and circulating lymphocytes. CD85 a membrane protein present on plasma cells, B cells, and monocytes. CD86 a membrane protein present on some germinal-center B cells, mitogen-activated B cells, and monocytes that serves as a B-cell activator; expressed in anaplastic large cell lymphomas, on Reed-Sternberg cells, and on Epstein Barr virus–transformed B cells. CD87 a glycosylphosphatidylinositol-anchored membrane protein present on activated T cells, monocytes, and activated neutrophils that plays a role in cell-surface plasminogen activation; expressed on macrophages at sites of inflammation. CD88 a type III transmembrane protein present on neutrophils, macrophages, eosinophils, mast cells, and smooth muscle cells that helps trigger chemotaxis and aids in cellular activation, respiratory burst, and degranulation; expressed in monocytoid tumors. CD89 a type I transmembrane protein present on neutrophils, monocytes, macrophages, and some T and B cells that assists in triggering granulocyte respiratory burst; expressed in monocytoid tumors. CDw90 a glycosylphosphatidylinositol-anchored membrane protein of unknown function present on prothymocytes and in brain and other nonlymphoid tissues. CD91 a membrane protein on monocytes and macrophages that may facilitate endocytosis. CDw92 a membrane protein present on neutrophils, platelets, and monocytes; of unknown function. CD93 a membrane protein present on neutrophils, monocytes, and endothelial cells; of unknown function. CD94 a membrane protein expressed on natural killer cells and a few T cells that stimulates natural killer cell cytolysis and release of tumor necrosis factor. CD95 a type I transmembrane protein present on T cells and myeloid cells that may induce apoptosis. CD96 a type I transmembrane protein present on T cells, natural killer cells, and activated B cells that is expressed primarily upon cellular activation, suggesting ligand-binding activity. CD97 a membrane protein of unknown function present on monocytes and mature granulocytes. CD98 a type II transmembrane protein present on monocytes, cardiac muscle cells, endothelial cells, T cells, B cells, and natural killer cells; probably involved in regulating calcium fluxes; increased on T cells in some autoimmune disease or in chronic hepatitis. CD99 a type I transmembrane protein present on thymocytes, lymphocytes, and myeloid cells involved in rosette formations with sheep erythrocytes. CD99r a type I transmembrane protein similar to CD99 but present on myeloid cells. CD100 a membrane protein present on hemopoietic cells that can induce proliferative responses. CDw101 a membrane protein of unknown function present on neutrophils, monocytes, and some T cells. CD102 a type I transmembrane protein present on endothelial cells, platelets, monocytes, dendritic cells, subsets of lymphocytes, and in splenic sinusoids that may facilitate recirculation of memory T cells. CD103 a type I transmembrane protein present on intestinal intraepithelial lymphocytes, some circulating leukocytes, and some T cells that facilitates adhesion to epithelia; expressed in hairy cell leukemia and some B-cell chronic lymphocytic leukemias. CD104 a type I transmembrane protein present on epithelia and thymocytes that facilitates adhesion of cells to the extracellular matrix; expressed in squamous cell carcinoma. CD105 a type II transmembrane protein present on endothelium, proerythryoblasts, activated monocytes and macrophages, and follicular dendritic cells that may play a role in adhesion; expressed in leukemic cells of B-lymphoid and myeloid origin. CD106 a type I transmembrane protein present on activated endothelial cells, macrophages, dendritic cells, marrow stroma, myoblasts, and myotubules that facilitates recruitment of leukocytes to sites of inflammation. CD107a a type I transmembrane protein present on activated platelets; increased expression noted on transformation of cells with metastatic potential and on embryonic cells. CD107b a type I transmembrane protein present on activated platelets; increased expression noted on transformation of cells with metastatic potential and on embryonic cells. CDw108 a glycosylphosphatidylinositol-anchored protein of unknown function present on activated T cells. CDw109 a glycosylphosphatidylinositol-anchored membrane protein of unknown function present on activated T cells, activated platelets, and endothelial cells. CD115 a type I transmembrane protein present on placenta, macrophages, monocytes, and monocyte-precursors that is involved in proliferation and differentiation of monocytes and their progenitors; expressed in choriocarcinomas. CDw116 a type I transmembrane protein present on monocytes, granulocytes, endothelial cells, dendritic cells, and fibroblasts that stimulates cell proliferation and differentiation; expressed in osteogenic sarcoma and breast and lung carcinomas. CD117 a type I transmembrane protein present on hemopoietic progenitors, mast cells, melanocytes, spermatogonia, oocytes, and some natural killer cells that assists in signal transduction to transfected cell lines; expressed in colon carcinomas. CD120a a type I transmembrane protein present on many cell types that has a high affinity for tumor necrosis factors. CD120b a type I transmembrane protein present on many cell types that has a high affinity for tumor necrosis factors. CDw121a a type I transmembrane protein present on T cells, thymocytes, chondrocytes, synovial cells, endothelial cells, fibroblasts, keratinocytes, and hepatocytes that aids in stimulation of cellular proliferation and/or activation. CDw121b a type I transmembrane protein present on B cells, monocytes, and macrophages that is involved in interaction with interleukins. CDw122 a type I transmembrane protein present on activated T cells, B cells, monocytes, and natural killer cells that may complex with CD25. CD123 a type I transmembrane protein present on pluripotent stem cells and committed hemopoietic progenitor cells that is involved in cell proliferation and/or differentiation. CDw124 a type I transmembrane protein present on mature B cells, T cells, epithelium, hemopoietic precursors, and fibroblasts that induces cell proliferation and/or activation; expressed in lymphomas and pancreatic, hepatic, and bladder tumors. CD125 a type I transmembrane protein present on eosinophils and basophils that stimulates cellular proliferation and/or differentiation. CD126 a type I transmembrane protein present on plasma cells, leukocytes, epithelial cells, fibroblasts, neural cells, and hepatocytes that stimulates cell growth and/or differentiation; possible growth factor for myelomas. CDw127 a type I transmembrane protein present on B-cell precursors, thymocytes, mature T cells, and monocytes that induces cell growth and/or differentiation. CDw128 a type III transmembrane protein present on neutrophils, basophils, monocytes, keratinocytes, and some T cells that induces chemotaxis and/or cell activation; expressed on melanoma cells. CD129 a type I transmembrane protein present on some T cells, myeloid and erythroid precursors, and mast cells that induces cell growth and/or differentiation; expressed in Hodgkin disease, large cell lymphomas, and megakaryoblastic leukemia. CDw130 a type I transmembrane protein present on most leukocytes, epithelial cells, fibroblasts, hepatocytes, and neural cells; interacts with leukemia inhibitor factors, interleukins, and other cell-proliferative factors.

cluttering (klut′er-ing)
A speech disorder usually occurring in childhood characterized by abnormally rapid rate, disturbed fluency, erratic rhythm, and poor articulation that makes it difficult to understand the speaker.

Clutton
Henry H., British surgeon, 1850–1909. See C. joints, under joint.

clysis (kli′sis)
1. An infusion of fluid, usually subcutaneously, for therapeutic purposes. 2. Formerly, a fluid enema; later, the washing out of material from any body space or cavity by fluids. [G. klysis, a drenching by a clyster]

-clysis
Combining form referring to injection or enema. [G. klysis, a drenching by a clyster]

clyster (klis′ter)
An old term for enema. [G. klyster, fr. klyzo, fut. klyso, to wash out]

C.M.
Abbreviation for Chirurgiae Magister, Master in Surgery.

CM-
Symbol for carboxymethyl radical.

Cm
Symbol for curium.

cM
Abbreviation for centimorgan.

cm
Abbreviation for centimeter; c.2 for square centimeter; c.3 for cubic centimeter.

CMA
Abbreviation for Certified Medical Assistant.

cmc
Abbreviation for critical micelle concentration.

CM-cellulose
SYN: carboxymethyl cellulose.

CMG
Abbreviation for cystometrogram.

CMI
Abbreviation for cell-mediated immunity.

CML
1. Abbreviation for cell-mediated lymphocytotoxicity. 2. Acronym for chronic myelogenous leukemia.

CMO
Abbreviation for calculated mean organism.

CMP
Symbol for cytidine 5′-monophosphate (secondarily, for any cytidine monophosphate).

c-mp1
A cell-surface receptor on megakaryocytes, platelets, and CD34-positive hematopoietic precursor cells; appears to be the receptor for regulation of megakaryocytopoiesis and platelet production.

CMT
Abbreviation for Certified Medical Transcriptionist. See medical transcriptionist.

CMV
1. Abbreviation for controlled mechanical ventilation; Cytomegalovirus. 2. A cancer drug combination treatment consisting of cisplatin, methotrexate, and vinblastine, used in the treatment of bladder and other malignancies.

cnemial (ne′me-al)
Relating to the leg, especially to the shin. [G. kneme, leg]

cnemis (ne′mis)
The shin. [G. knemis (knemid-), a legging]

cnida, pl .cnidae (ni′da, ni′de)
SYN: nematocyst. [G. knide, nettle]

cnidocyst (ni′do-sist)
SYN: nematocyst.

Cnidospora (ni-do-spor′a)
SYN: Microspora. [G. knide, nettle, sea nettle, + sporos, seed]

Cnidosporidia (ni′do-spo-rid′ea)
SYN: Microsporida. [G. knide, nettle, sea nettle, + Mod. L., fr. G. sporos, seed]

C.N.M.
Abbreviation for certified nurse-midwife.

CNS
1. Abbreviation for central nervous system. 2. Symbol for the thiocyanate radical, C.− or &cbond;C..

CO
Symbol for carbon monoxide.

Co
Symbol for cobalt; coccygeal.

58Co
Symbol for cobalt-58.

60Co
Symbol for cobalt-60.

57Co
Symbol for cobalt-57.

co-
See con-.

CoA
Abbreviation for coenzyme A.

coacervate (ko-as′er-vat)
An aggregate of colloidal particles separated out of an emulsion (coacervation) by the addition of some third component (coacervating agent). [L. coacervare, pp. -atus, to collect in a mass]

coacervation (ko-as-er-va′shun)
Formation of a coacervate.

coadaptation (ko′ad-ap-ta′shun)
The operation of selection jointly on two or more loci.

coagglutination (ko-a-gloo′tin-a′shun)
Aggregation of particulate antigens bound with agglutinins of more than one specificity.

coagula (ko-ag′u-la)
Plural of coagulum.

coagulable (ko-ag′u-la-bl)
Capable of being coagulated or clotted.

coagulant (ko-ag′u-lant)
1. An agent that causes, stimulates, or accelerates coagulation, especially with reference to blood. 2. SYN: coagulative.

coagulate (ko-ag′u-lat)
1. To convert a fluid or a substance in solution into a solid or gel. 2. To clot; to curdle; to change from a liquid to a solid or gel. [L. coagulo, pp. -atus, to curdle]

coagulation (ko-ag-u-la′shun)
1. Clotting; the process of changing from a liquid to a solid, said especially of blood ( i.e., blood c.). In vertebrates, blood c. is a result of cascade regulation from fibrin. 2. A clot or coagulum. 3. Transformation of a sol into a gel or semisolid mass; e.g., the c. of the white of an egg by means of boiling. In any colloidal suspension, the dispersion of the disperse phase from the continuous phase is greatly reduced, thereby leading to a complete or partial separation of the latter; usually an irreversible phenomenon unless the basic nature of the substance is chemically altered. disseminated intravascular c. (DIC) a hemorrhagic syndrome that occurs following the uncontrolled activation of clotting factors and fibrinolytic enzymes throughout small blood vessels; fibrin is deposited, platelets and clotting factors are consumed, and fibrin degradation products inhibit fibrin polymerization, resulting in tissue necrosis and bleeding. SEE ALSO: consumption coagulopathy.

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