ASSESSMENT OF CELL-PROLIFERATION IN NORMAL AND PATHOLOGICAL BONE-MARROW BIOPSIES - A STUDY USING DOUBLE SEQUENTIAL IMMUNOPHENOTYPING ON PARAFFIN SECTIONS

The proliferative activity of the haematopoietic and plasma cells in b one marrow was evaluated under normal and neoplastic conditions, by me ans of a sequential double immunostaining technique, using monoclonal antibody MIB-1 recognizing the cell proliferation-associated nuclear a ntigen Ki-67, and antibodies against glycophorin-C, myeloperoxidase, f actor VIII-related antigen, and immunoglobulin light chains, Fifty-eig ht B5 fixed, paraffin-embedded bone marrow biopsies were analysed, inc luding 11 normal controls, 10 cases of myelodysplasia, 14 cases of chr onic myeloproliferative disorder, eight cases of acute non-lymphoid le ukaemia, and 15 cases of myeloma, In normal marrows, the highest proli ferative activity was noticed in the erythroid cells (75% to 95%; mean 90%), in comparison with myeloid precursors (15% to 80%; mean 38%), a nd megakaryocytes (10% to 20%; mean 14%); no Ki-67 positive plasma cel ls were found, In all investigated haematological disorders, the expre ssion of MIB-1 by erythroid cells was similar to that observed in cont rols, Similarly, the percentage of MIB-1+ myeloid precursors in chroni c myeloproliferative disorders and myelodysplasia largely overlapped t he values observed in normals, and comparable values were also found i n the blast cells from acute non-lymphoid leukaemia type M1 and M2. Th ese findings suggest that the evaluation of either erythroid or myeloi d proliferative activity is of little value in the differential diagno sis between these myeloproliferative disorders, By contrast, the obvio us increase of Ki-67 expression of megakaryocytes in chronic myeloprol iferative disorders, with labelling also of micro-megakaryocytes, migh t sustain the diagnosis in controversial cases. Since cases of mature myeloma showed less than 2% of Ki-67 positive cells, evaluation of pro liferative activity is of no value in the differential diagnosis with reactive plasmacytosis: The sequential double immunophenotyping for Ki -67 antigen and for haematopoietic cell lineage-associated markers can be applied in a consistent manner to routine bone marrow biopsies to evaluate proliferating cells in normal and neoplastic conditions.