Immunocytochemical analysis of MNDA in tissue sections and sorted normal bone marrow cells documents expression only in maturing normal and neoplastic myelomonocytic cells and a subset of normal and neoplastic B lymphocytes

The human myeloid cell nuclear differentiation antigen (MNDA) is a nuclear antigen known to be expressed in mature myelomonocytic cell Lines. An exten sive immunocytochemical evaluation of fixed tissues confirmed MNDA expressi on in normal maturing granulocytes and monocytes and in acute nonlymphocyti c leukemias and chronic myelogenous leukemia. MNDA was not detected in norm al tissue histiocytes but was found in activated macrophages and foreign bo dy giant cells associated with inflammation. Flow cytometric cell sorting o f normal bone marrow established that MNDA is initially expressed in myeloi d blast cells. Examination of lymphoid tissues showed a low level of expres sion in a population of normal mantle B lymphocytes but not in germinal cen ter cells or plasma cells. A subset of B cell neoplasms expressing MNDA inc luded hairy cell leukemia, parafollicular (monocytoid) B cell lymphoma, man tle cell lymphoma, and small lymphocytic lymphoma. Cell sorting of normal b one marrow showed MNDA expression in CD20(+)/CD10(-)/CD5(-) B cells. MNDA w as not detected in other normal bone marrow or all other nonhematopoietic c ells. The hematopoietic cell-specific pattern of MNDA expression was elucid ated through a comprehensive analysis of normal and neoplastic tissues, and the results protide further evidence of the coexpression of B- and myeloid cell markers in neoplastic B cells and identify a normal B cell population that might be related to the cell of origin of a subset of B cell neoplasm s. HUM PATHOL 30:1040-1049. Copyright (C) 1999 by W.B. Saunders Company.