Gene Expression of MPO (Myeloperoxidase) in Acute Undifferentiated Leukemia

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Acute leukemia cells negative for Cytochemical (cy) MPO (Myeloperoxidase) are classified as Acute Lymphoblastic Leukemia (ALL). Some ALL cells, however, express myeloid antigen (CD13/33). The estimation of MPO gene expression by such ALL/lymphoma cells is the purpose of this project, thereby having a deeper insight into the classification of cy-MPO-negative leukemia/lymphoma cells and the normal hematopoietic differentiation scheme.Among the collected 17 cases of Pre-B ALL cells co-expressing CD13/33 antigen 15 cases were negative for electronmicroscopical (em) MPO and MPO RNA. Only 2 cases were positive for em-MPO and MPO RNA. The former group was positive for HLA-DQ antigen, but the latter negative.As to neoplastic T cells, 12 cases of mature type cells (positive for CD1, 3, 4, 8) did not even express CD13/33 antigen. Nine cases of immature type of cells (CD7, 7+5, 7+2, 7+5+2) always expressed CD13/33 antigen. In 2 out of the 9 cases, em-MPO and MPO RNA were positive. This result was particularly intriguing in relation to AML conversion of immature neoplastic T cells.Cytokine or chemical compound introducing or enhancing MPO expression was not found. It was found, however, that gammaIFN suppresses the gene expression of MPO. This observation is very original, since no similar report has appeared in literatures.