Epitope-sharing between Mycoplasma arthritidis and chondrocytes demonstrated by monoclonal antibodies

Polyclonal and monoclonal antibodies against Mycoplasma (M.) arthritidis membranes were investigated in the indirect immunofluorescence test (IIFT) and enzyme immunoassay (EIA) for their reactivity with rat and human chondrocytes as well as with rat skin fibroblasts. The monoclonal antibody A 79 gave positive reactions with rat chondrocytes in the IIFT up to a dilution off 1: 128 and in EIA up to a dilution of 1:16. In the EIA, the monoclonal antibodies A 31, A 32 and A 58 recognized M. arthritidis as well as rat and human chondrocyte membrane antigens up to dilutions of 1:128 and 1:256 and rat skin fibroblasts up to dilutions of 1:32/64. In the IIFT, the whole surfaces of the rat and human chondrocytes were strongly fluorescing after the treatment with the polyclonal antiserum against M. arthritidis. The monoclonal antibody A 79 caused weak fluorescence (rat chondrocytes) or no fluorescence (human chondrocytes) on the surface of the chondrocytes but a stronger fluorescence on areas around and between them. From these results it can be concluded that A 79 probably reacts with antigens of the chondrocyte matrix.