Elevated autoantibody content in rheumatoid arthritis synovia with lymphoid aggregates and the effect of rituximab
Rosengren S et al. – Combined with earlier observations that synovial lymphoid aggregates survived rituximab treatment, these data suggest that lymphoid aggregates may provide a protective niche for autoantibody producing cells. Methods- Study to evaluate the contribution of synovial lymphoid aggregates to autoantibody, total immunoglobulin production in RA pts, and the effect of the B-cell depleting ab, rituximab
- Autoantibodies, total IgM and IgG were quantified by ELISA in extracts of synovial tissues and matched serum
- Synovial biopsies and serum were obtained at baseline and 8 wks following rituximab therapy in 14 RA pts
Results- Anti-CCP IgG, but not RF-IgM, was enriched in RA synovia vs serum
- Total IgM and IgG was also enriched in RA, but not in OA
- SSI correlated with mRNA content for both IgM and IgG
- RA synovia with lymphocyte aggregates contained elevated RF-IgM and anti-CCP IgG vs tissues with diffuse lymphoid infiltration
- Rituximab treatment did not affect synovial autoantibody or total Ig SSI overall
- In aggregate-containing tissues, rituximab reduced total IgM and IgG SSI as well as IgM and IgG1 mRNA
- RF-IgM and anti-CCP IgG synovial/serum indices were unchanged by rituximab in aggregate-containing synovial
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