The United States Biological Proteinase-3, Human, BioAssay? ELISA Kit is intended for the detection and semi-quantitative determination of antibodies to PR-3 in human serum. The assay is to be used to detect antibodies in a single serum specimen. Proteinase-3 is a lysosomal enzyme that can be found in human neutrophils. There are two subsets of autoantibodies to sample neutrophils, c- ANCA and p-ANCA. The first subtype, c-ANCA, shows cytoplasmic staining by IFA and is diagnostic for Wegener's granulomatosis. The major antigen responsible for the c-ANCA staining is Proteinase-3. The second subtype, p- ANCA, shows perinuclear staining by IFA. The major antigen responsible for the p-ANCA response has been shown to be myeloperoxidase. The ANCA staining patterns are obtained using ethanol-fixed sample neutrophils. Anti- PR-3 autoantibodies have been associated with Wegener's granulomatosis but less often with microscopic polyangiitis. Other antigen specificity's (CAP 57) can be respon