TY - JOUR T1 - Selective IgA immune unresponsiveness to Proteus mirabilis fumarate reductase A-chain in rheumatoid arthritis. JF - The Journal of Rheumatology JO - J Rheumatol SP - 1208 LP - 1212 VL - 32 IS - 7 AU - Richard H Weisbart AU - Yoon Min AU - Andrew L Wong AU - Joanne Kang AU - Suchada Kwunyeun AU - Antony Lin AU - Joon Kim AU - Grace Chan AU - Rika Wakelin AU - William Sohn AU - Sophia S Chang AU - Robert N Nishimura Y1 - 2005/07/01 UR - http://www.jrheum.org/content/32/7/1208.abstract N2 - OBJECTIVE: To determine if selective immune unresponsiveness to microbial antigens is associated with predisposition to rheumatoid arthritis (RA). METHODS: Proteins from Proteus mirabilis lysate were isolated by SDS-PAGE and examined by Western blotting for antibody responses in sera from patients with RA compared to healthy subjects and patients with psoriatic arthritis (PsA). RESULTS: Although RA patients had marked IgA immune responses to many P. mirabilis proteins compared to healthy subjects, selective unresponsiveness was found in RA to a 66 kDa protein identified as fumarate reductase A-chain (FRD-A) by mass spectroscopy. This was confirmed in Western blots with recombinant FRD-A from P. mirabilis. IgA unresponsiveness to FRD-A was found in 21/59 (35.6%) RA patients compared to 7/63 (11.1%) healthy individuals (p < 0.01) and 6/52 (11.5%) patients with PsA (p < 0.01). IgA unresponsiveness to FRD-A was present in 20/46 (43.5%) RA patients with IgA rheumatoid factors (RF) compared to 1/13 (7.7%) without RF (p < 0.025). CONCLUSION: Our results identify a selective hole in the IgA immune repertoire for P. mirabilis FRD-A in a subset of IgA RF-positive patients with RA. ER -