A monoclonal antibody (anti-L-35) which reacts with human osteoclasts and cells of the mononuclear phagocyte system.

The immunohistochemical reactivity of a monoclonal antibody, anti-L-35, on a wide range of tissues is described. Anti-L-35 showed a high specificity for known and presumptive cells of the mononuclear phagocyte system including monocytes, sinus histiocytes, tangible body macrophages, interdigitating reticulum cells, Kupffer cells, alveolar macrophages, microglia, synoviocytes and Langerhans cells. Anti-L-35 also stained osteoclasts in fetal and adult bone including osteoclast-like giant cells of the giant-cell tumour of bone. Anti-L-35 did not react with any other cell type in the tissues screened apart from renal proximal tubular epithelium and megakaryocytes. This study has shown that L-35 is not restricted to activated T-cells, as previously reported, and provides further immunohistochemical evidence that monocytes, macrophages and osteoclasts contain common cellular antigens.