The deposition of immunoglobulins and complement in osteoarthritic cartilage

In a prospective study of 117 patients having reconstructive surgery for osteoarthritis, biopsies of hyaline articular cartilage and meniscal fibrocartilage were taken which exhibited immunofluorescence in their articular surfaces, for at least two immuno-globins (Ig) and beta 1c. These could represent immune complexes. The cases were classified into three Groups according to clinical, radiological and laboratory features, (1) non-arthritic -- 27 (3% positive); (2) secondary degenerative -- 32 (16% positive); (3) idiopathic osteoarthritic -- 89 (51% positive). The incidence of positive findings in Group III was significant at p less than 0.001 and less than 0.005 levels respectively as compared to those of Groups I and II. Our study of the disease features and their associated laboratory parameters indicated the following: positive findings correlated with an older mean age and longer disease duration. The gradings for mononuclear cell infiltration in synovial biopsies of Group III were more than two times higher than those of secondary arthritics. Group III also had an increased incidence of circulating auto-antibodies. A careful review of clinical features has not suggested a mixed population with rheumatoid disease but rather that Group III represents part of the spectrum of primary generalised osteoarthritis. These data suggest involvement of local immune mechanisms in cartilage degradation in the joints of those patients with longer term involvement.