Induction of B-lymphocyte antigens on the chronic myeloid leukemic cell line K562 using sodium butyrate

Chronic myeloid leukemia (CML) is a disorder arising from a defect in the hemopoietic stem cell. Consequently, the malignant clone can involve all cells within the stem cell's capacity for differentiation, including erythrocytes, granulocytes, monocytes, megakaryocytes, and lymphocytes. Similarly, the K562 cell line, which was derived from a patient with CML, has been shown to be capable of differentiation towards erythrocytes, granulocytes, monocytes, and megakaryocytes, and in this respect may represent a model of the hemopoietic stem cell. However, although K562 shows properties of a myeloid stem cell, no lymphocyte-specific features or differentiation have yet been described. In the present study, K562 cells have been induced to differentiate by culture in the presence of sodium butyrate. The direction and extent of induced differentiation over 12 days were determined with a panel of monoclonal antibodies and with cytochemical stains. This treatment consistently induced expression of pre-B-cell markers, including B-lymphocyte-specific B4 and B1, and of the common acute lymphoblastic leukemia antigen (CALLA), recognized by J5. In addition to the increased expression of B-lymphocyte markers, butyrate induction of K562 resulted in a decrease in granulocyte markers, increases in certain monocyte and platelet markers, and an increase in beta 2 microglobulin expression. Butyrate-induced expression of B-lymphocyte markers was not observed with the myelomonocytic cell line U937. The expression of B-lymphocyte-specific antigens on butyrate-induced K562 may result from the relaxed control of gene expression, but alternatively these observations may indicate the lymphoid-myeloid stem cell nature of K562.