MONOCYTE-MACROPHAGE ANTIGEN EXPRESSION ON CHONDROCYTES

Objective. To characterize chondrocytes in normal and arthritic joints and compare their phenotype to that of synovial macrophages present i n rheumatoid joints. Methods. Using an immunoperoxidase staining techn ique, we examined the presence and distribution of a number of leukocy te activation and differentiation antigens on samples of cartilage obt ained from resected joints of normal controls and subjects with rheuma toid arthritis or osteoarthritis. Results. Chondrocytes in each group were CD14+, CD68+, Thy-1+, CD11a+, CD18+, MAX.3-, and MAX.24-. Stainin g was variable for MAX.1 and CD45. HLA-DR and CD71 were expressed only on cells located in the superficial layer of rheumatoid cartilage, We found lower levels of expression of CD14 on chondrocytes in arthritic joints, whereas CD58 was expressed at higher levels. Surface expressi on of CD14 was confirmed on normal chondrocytes using flow cytometry a nd further supported by the detection of CD14 mRNA by polymerase chain reaction. Conclusion. Our findings demonstrate that chondrocytes expr ess several antigens that are also found on monocytes and macrophages.