*C

CAP-SYSTEM The CAP-system is an automatic test system that is widely used to measure allergen-specific IgE antibodies and autoantibodies (see autoimmunity). The principle of this assay is that of a nonradioactive immunoassay. To measure antibodies, allergen or antigen is bound to cellulose, which provides a large surface for binding resulting in high sensitivity of the test. The system is also used to measure cell-specific proteins such as tryptase and eosinophil cationic protein (ECP). Increased tryptase levels indicate mast cell activation (e.g., during anaphylaxis), whereas increased ECP levels suggest eosinophil activation (e.g., in asthma).