Cellular immune responses to cartilage components in rheumatoid arthritis and osteoarthritis: a review and report of a study.

Proliferative responses of peripheral blood mononuclear cells of rheumatoid or osteoarthritis patients and normal controls stimulated with cartilage components were studied. Two components not studied in previous cellular studies, matrix proteins (fraction A4) and lipoproteins, were used as well as whole extract of cartilage, native and denatured collagen, and proteoglycans. In general, osteoarthritis cells responded less well than the other two groups; this was statistically significant for fraction A4-matrix protein (normal p less than .02, rheumatoid arthritis p less than .025). Fraction A4 sterilized by filtration rather than irradiation gave higher responses in both arthritic groups, but not controls. Antigenic alteration by radiation may explain this difference and, perhaps, the low level of proliferation to all the components seen. The possible role of such cell-mediated responses in chronic arthritis is discussed, and the current and previous reports of cartilage component-induced cellular responses are reviewed.