Matrix metalloproteinase MMP-19 (RASI 1) is expressed on the surface of activated peripheral blood mononuclear cells and is detected as an autoantigen in rheumatoid arthritis

In order to characterize the autoimmune response participating in the pathogenesis of rheumatoid arthritis (RA) a cDNA expression library constructed from mRNAs which had been isolated from the inflamed synovium of an RA patient was screened with autologous IgG autoantibodies. This led to the identification of gene rasi-1 which encodes a protein showing sequence identity with the zinc-binding matrix metalloprotoinase MMP-19. MMP-19 is detected on the surface of activated PBMCs, T(H)1 lymphocytes, and Jurkat T lymphoma cells. It exhibits gelatinolytic activity and is recognized by autoantibodies in 26% and, respectively, 33% of sera collected from Rk patients and systemic lupus erythematosus (SLE) patients. The novel autoantigen MMP-19 thus could play a role in the pathological processes participating in RA-associated joint tissue destruction.