Expression of a New Cellular Protein by Monocytoid B-Lymphocytes Differentiated from the Acute Lymphoblastic Leukemia...

In an attempt to identify differentiation-related changes in cellular proteins, the common acute lymphoblastic leukemia (ALL) cell line, REH, was studied. REH cells were cultured in either the absence or presence of 12-0-tetradecanoylphorbol-13-acetate (TPA). Changes in surface phenotype were analyzed using monoclonal antibodies and flow cytometry. Cellular proteins were analyzed with two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) of [(3)H]leucine and [(32)P]orthophosphate labeled cells. Immunophenotype and 2D-PAGE studies were replicated three times on untreated (control) and TPA-treated cells on day 5. Immunophenotypic analysis showed that TPA induced further differentiation of REH cells along the B-cell lineage as indicated by significant decrease in the expression of CD10, induction of CD11c and increase in the expression of CD22. 2D-PAGE of [(3)H]leucine but not the [(32)P]orthophosphate showed that TPA induced the expression of a unique protein. The apparent relative molecular mass (Mr) of the resolved protein was ~23 kd with a ~6.2 isoelectric point (PI). Based on the morphologic and phenotypic findings, our data suggest that the new protein (p23-6.2) and the quantitative changes in protein synthesis induced by TPA are differentiation-related. Our study also indicates that 2D-PAGE analysis is a sensitive and complementary tool to phenotypic markers in the study of differentiation of malignant B-cells.