Glossary C

• Cytotoxic T cell: T cells that bear the CD8 marker and function to kill virus-infected cells and tumor cells by triggering apoptosis.
• C1 inhibitor (C1 - INH): A glycoprotein that acts to dissociate Clr and C1s from C1q, thus inhibiting the first active enzyme formed in the classical complement cascade
• C3 glomerulopathies (C3G): Diseases involving the glomeruli of the kidneys
• C4 - binding protein (C4BP): A protein in the complement system that serves as a cofactor for factor 1 in the inactivation of C4b
• Cancer: A disease characterized by the presence of a malignant tumor
• Cancer antigen 125 (CA 125): A glycosylated protein that is used clinically as a marker for ovarian cancer
• Cancer vaccines: Vaccines that have been developed for the purpose of preventing or treating cancer
• Candidiasis: An opportunistic fungal infection caused by Candida albicans and other Candida species
• Capture (sandwich) immunoassays: Immunoassays that detect an antigen by its ability to bind to an antibody attached to a solid phase as well as a detector antibody that contains a label, such as an enzyme
• Carcinoembryonic antigen (CEA): An oncofetal protein that may be elevated in patients with cancers of the breast, gastrointestinal tract, pancreas, or lung
• Carcinogenesis: The process by which a cell is transformed into a malignant tumor
• Carcinoma: Malignant tumor derived from the skin or epithelial linings of internal organs or glands
• CAR - T cells: Genetically modified T cells possessing a chimeric antigen receptor that binds to an antigen that can serve as a target for adoptive immunotherapy
• Cascade: A series of steps that occur in a progressive manner, for example, the classical pathway of complement or the secretion of a cytokine by a cell that activates target cells to produce additional cytokines
• CD4 T cell: Type of lymphocyte that provides help to B cells to initiate antibody production (T helper cell) or, less commonly, inhibits the immune response (T regulatory cell)
• CD45: A leukocyte marker present on all white blood cells (WBCs); used to identify WBC populations in flow cytometry analyses
• Celiac disease: An autoimmune disease affecting the small intestine and other organs
• Cell cycle: The sequence of events that occurs between cell divisions and consists of the following phases: G1 (Gap 1), S (DNA synthesis), G2 (Gap 2), and M (Mitosis)
• Cell - mediated immunity: A type of immunity in which T cells produce cytokines that help to regulate both the innate and adaptive immune response
• Central tolerance: Destruction of potentially self - reactive T and B cells as they mature in either the thymus or the bone marrow
• Competitive immunoassay: An immunoassay in which unlabeled and labeled antigen compete for a limited number of binding sites on reagent antibody
• Congenital syphilis: The transfer of syphilis from an infected mother to her fetus during pregnancy
• CREST syndrome: A subset of scleroderma named after its five major features: calcinosis, Raynaud’s phenomenon, esophageal dysmotility, sclerodactyly, and telangiectasia
• C - reactive protein (CRP): A trace constituent of serum that increases rapidly following infection or trauma to the body and acts as an opsonin to enhance phagocytosis
• Cross - reactivity: A phenomenon that occurs when an antibody reacts with an antigen that is structurally similar to the original antigen that induced antibody production.
• Cryoglobulins: Immunoglobulins of the immunoglobulin M (IgM) or IgG class that precipitate at cold temperatures, causing occlusion of blood vessels in the extremities if a patient is exposed to the cold
• Conidia: Asexual reproductive structures produced by fungi at the tip of hyphae; also known as spores
• Conformational epitope: Key antigenic site that results from the folding of one chain or multiple chains, bringing certain amino acids from different segments of a linear sequence or sequences into close proximity with each other so that they can be recognized together
• Complement - dependent cytotoxicity (CDC): Killing of cells that results from attachment of antibody with activation of complement
• Coombs reagent: An anti - human immunoglobulin reagent used to enhance the detection of immunoglobulin G (IgG) antibodies in blood bank testing
• Complement receptor type 1 (CR1): A cell - bound regulator of complement activation. It assists in degrading C3b and C4b and mediates transport of C3b-coated immune complexes to the liver and spleen.
• Control mean: The average of all data points
• Community immunity: Concept of extending protection to unvaccinated individuals by reducing spread of an infection when a significant proportion of individuals in the population have been immunized; also known as herd immunity
• Constant region: The carboxy - terminal segment of antibody molecules (half of immunoglobulin light chains plus three - quarters of heavy chains) that consists of a polypeptide sequence found in all chains of that type
• Complement: A series of proteins that are normally present in serum and whose overall functions are mediation of inflammation and destruction of foreign cells
• Contact dermatitis: A delayed hypersensitivity reaction caused by T - cell sensitization to lowmolecular - weight compounds, such as nickel and rubber, that come in contact with the skin
• Crossmatch: Incubation of donor lymphocytes with recipient serum to determine the presence of antibodies, which would indicate rejection of a potential transplant
• Cryptococcosis: A fungal disease caused by Cryptococcus neoformans and characterized as a pulmonary infection that may spread to the central nervous system and the brain
• C - type lectin receptors (CLRs): Plasma - membrane receptors found on white blood cells (WBCs) that bind to mannan and β - glucans in fungal cell walls

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• Complementary or copy DNA (cDNA): A DNA sequence made from ribonucleic acid (RNA) using the enzyme reverse transcriptase and nucleotide base - pairing rules