Reactivity of normal rat epiphyseal chondrocytes with monoclonal antibodies recognizing different leucocyte markers

The aim of the study was to test whether normal rat epiphyseal chondrocytes react with monoclonal antibodies (MoAbs) detecting different markers of lymphoid cells. For this purpose, isolated chondrocyte and, for comparison, splenocyte cytosmears were exposed to a battery of different MoAbs followed by indirect immunoperoxidase staining. As we were able to show, all chondrocytes reacted with OX17 MoAb detecting Class II (Ia) antigen encoded by the RT1.D subregion of rat major histocompatibility complex (MHC). However, unlike splenocytes they did not react with OX6 MoAb detecting the RT1.B encoded Class II molecule. Moreover, all chondrocytes were stained with W3/25 MoAb specific for the rat equivalent of human CD4 (T4) antigen and with W3/13 MoAb specific for rat leucocyte sialoglycoprotein. A positive reaction was also obtained with the antibody against the S-100 protein. By contrast, chondrocytes did not react with antibodies specific for all T (OX19) or B (HIS14) cells, rat CD8 (T8) equivalent, monocytes/macrophages (ED1, ED2), factor VIII (M616), or glial fibrillary acidic protein (Z334).