Use of monoclonal antibodies to recognise osteoclasts in routinely processed bone biopsy specimens.

In decalcified (5% nitric acid) and undecalcified (glycol-methacrylate or resin embedded) routinely processed bone specimens osteoclasts against resorbing surfaces were identified with monoclonal antibodies directed against leucocyte common antigen (LCA) (PD7/26, 2B11), CD68 (KP1), and gpIIIa (Y2/51) but not against HLA-DR (CR3/43 and Ta11B5). Mononuclear cells on resorbing surfaces and occasional mononuclear cells against or near resting surfaces showed a similar pattern of reactivity. This study shows that immunohistochemistry is a sensitive and useful technique for identifying osteoclasts in routinely processed bone specimens. It also suggests a role for mononuclear cells (possibly pre-osteoclasts) in bone resorption.