摘要: Aspartic proteases are widely distributed enzymes found in all organisms including microorganisms, protozoa, vertebrates, viruses and plants. These enzymes are highly conserved and share sequence homologies especially around the active site. We investigate the antigenic features of two members of this family: pepsin and cathepsin D. Cathepsin Dis a lysosomal enzyme involved in antigen processing and matrix degradation. Peripheral blood lymphocytes were stimulated for 7 days in bulk cultures with human cathepsin D, bovine cathepsin D and porcine pepsin. After 6 days 3H-thymidine was added and 18 hours later proliferation was measured. We tested cells derived from patients with rheumatoid arthritis (RA), reactive arthritis, Lyme disease or mixed connective tissue disease. As controls we used age-matched healthy donors and patients with non-autoimmune diseases. 51% of the tested patients were …