IMMUNOTYPING OF BLASTS IN HUMAN BONE-MARROW

The diagnostic potential of immunocytochemical investigation of human bone marrow has not been fully realized due to difficulties in morphol ogical identifying of immunostained cells. We used an indirect immunop eroxidase technique after May-Grunwald-Giemsa staining for simultaneou s morphological and immunocytochemical analysis of blasts in human bon e marrow. Six healthy bone marrow donors were investigated. Most blast s I expressed CD34, CD38 and HLA-DR. Expression of c-kit (CD117) was o bserved on 42+/-9% of blasts I. Granulocytomonocytopoietic character w as demonstrated by expression of CD13 (33+/-15%) and CD45RA (23+/-10%) and erythropoiet ic character was demonstrated by expression of CD36 (22+/-8%) and CD45RO (30+/-11%). A very low proportion of blasts I wer e Thy-1 and CD61 positive; 34+/-6% of blasts I expressed CD22, represe nting B lymphoid committed progenitors. CD3, CD15, and gly cophorin A expression was not detected. Blasts II and III and proerythroblasts di d not show CD34 positivity. We conclude that blasts I are morphologica lly identifiable cells with a high percentage of CD34, CD38, and HLA-D R positivity. They are a pool of committed progenitor cells for erythr opoiesis, granulocytomonocytopoiesis, megakaryocytopoiesis, and B cell development. Blast II and proerythroblast represent the first morphol ogically identifiable cells of granulocytopoiesis and erythropoiesis.