Assessment of cell proliferation in paraffin sections of normal bone marrow by the monoclonal antibodies Ki-67 and PCNA.

Assessment of the proliferative index of human bone marrow using immunohistology in tissue sections offers practical advantages over other techniques. It is simpler to perform and can be applied to archival material. Progress in this area has been hampered by technical problems. Ki-67 studies, limited to fresh or frozen tissues, have been contradictory, and the labeling indices have been criticized for being unrealistically low. Proliferating cell nuclear antigen (PCNA) studies have also been considered unreliable because labeling indices include nondividing cells. We stained 82 routinely processed nonneoplastic bone marrow biopsies for Ki-67 equivalent MIB 1 antibody and PCNA/PC10 using a microwave oven antigen retrieval technique. 44.7% +/- 12.0 SD of the bone marrow cells stained with Ki-67/MIB 1. PCNA/PC10 staining gave similar results (50.7% +/- 12.3 SD). Pro- and basophilic erythroblasts, myeloblasts, promyelocytes, myelocytes, and megakaryocytes stained with both monoclonal antibodies in a manner consistent with known morphologic and cytokinetic data. Patients in different clinical groups showed similar mean values, the only exception being a group of cytokine-treated patients, which showed higher values than the other cases. Immunoperoxidase staining of bone marrow sections with Ki-67/MIB 1 and PCNA/PC10 monoclonal antibodies is a reliable method for assessing proliferation of hematopoietic cells.