The inflammatory role of immune complexes trapped in joint collagenous tissues

The inflammatory role of immune complexes trapped in joint collagenous tissues has been investigated. Joint collagenous tissues obtained from rabbits with antigen-induced arthritis generated mediators of acute inflammation when incubated with fresh normal rabbit serum as a source of complement. The role of trapped immune complexes in chronic inflammation was also studied by the surgical insertion of menisci, obtained from arthritic and control joints, into the suprapatellar pouches of previously immunized or naive recipient animals. It was shown that when immune complex containing menisci were inserted into immune rabbits, a chronic inflammatory capsule developed around the donor tissue, reminiscent of the inflammatory pannus seen in rheumatoid cartilage. Normal menisci and immune complex containing menisci inserted in naive animals developed capsules rich in fibroplasts and collagen fibres. Since we have previously shown the presence of immune complexes in the great majority of joint collagenous tissues obtained from patients with rheumatoid arthritis, our results suggest that these complexes may play a role in the formation of pannus, which constitutes a major mechanism responsible for cartilage destruction.