THE EXPRESSION OF MAJOR HISTOCOMPATIBILITY ANTIGENS ON HUMAN ARTICULAR CHONDROCYTES

Human articular chondrocytes were analyzed for major histocompatibilit y (MHC) antigens. The cells were obtained by enzymatic digestion of su rgical specimens from patients with osteoarthrosis and rheumatoid arth ritis having joint replacement. The analyses of Class I and Class II a ntigens were performed using microcytotoxicity techniques, as with con ventional human leukocyte antigen (HLA) typing, and by immunofluoresce nce on a flow cytometer with monoclonal antibodies. Eighty-five percen t of the chondrocytes had strong representation of Class I molecules, and individual specificities for HLA-A, HLA-B, and HLA-C could be dete cted. Class II antigens generally were not expressed on chondrocytes f rom noninflammatory states. In osteoarthrosis, some cells expressed HL A-DP and HLA-DQ, whereas in rheumatoid arthritis, there was an increas e in the expression of all Class II antigens. Incubation of chondrocyt es with gamma-interferon caused the strong induction of HLA-DR and HLA -DP, whereas HLA-DQ expression was largely unaffected. These results h ave broad implications for tissue transplantation and autoimmune disea se.