Table 1

The proposed major immunological, bacteriological, and anatomical factors in RA and SpA in the setting of HIV infection

Rheumatoid arthritis Spondyloarthropathy
MHC association—HLA-DR4MHC association—HLA-B27
CD4 T cells which contribute to inflammation are depleted in advanced HIVCD8 T cells also diminish but are spared compared with CD4 cells
Primary target tissuePrimary target tissue
The synovial membraneSites of increased biomechanical stress in the joints, especially the enthesis, adjacent marrow, capsules
Triggers—unknownTriggers—bacteria/virus (including HIV)
Rheumatoid factors?Genitourinary and bowel inflammation may be commoner in homosexuals, thus allowing greater access of bacteria to the circulation