MONOCLONAL-ANTIBODIES AGAINST HUMAN CHONDROCYTES

Cell-specific antigens are mainly found in cells or membrane surfaces rather than in the surrounding matrix. However, until now it was not p ossible to produce antibodies specific for cellular structures of chon drocytes, In 1989, Lance (Immunol. Lett. 21:63-73; 1989) first establi shed specific monoclonal antibodies for human articular chondrocytes t ested only by immunofluorescence. Studies describing the specificity o f these five antibodies (HUMC 1-5) and their relevance for immunohisto logical analysis of cartilage tissue were not available until now. The refore, the aim of the following study was to investigate the distribu tion of HUMC 1, 2, 3, 4 and 5 in mesenchymal cells in vivo and in vitr o immunohistochemically. Further investigations concentrate on the loc alization of chondrocyte specific antigens using immunoelectron micros copy, Immunohistological studies showed positive immunostainings with all five antibodies in human chondrocytes in. vivo and in vitro. A cro ss-reaction with human fibroblasts and osteoblasts for the antibodies HUMC 2 and HUMC 5 was observed. Furthermore, a parallel loss of immuno reactivity for HUMC 1, HUMC 3, and HUMC 4 was observed in cultured cho ndrocytes indicating that the specific antigens vanish during differen tiation observed in vitro. Subsequent immunoblot analysis employing co llagens as antigens did not show any reactivity. Using immunoelectron microscopy, gold particle labeling was observed in intracytoplasmatic vesicles of isolated chondrocytes. Our results indicate that HUMC 1, H UMC 3, and HUMC 4 are specific for cartilage cells and might be suitab le for immunohistological analysis of different cartilage tissues and pathologically altered chondrocytes.