Establishment of a common acute lymphoblastic leukemia cell line (LC4‐1) and effects of phorbol myristate acetate (PMA) on the surface antigen expression of the cell line

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Abstract
A common acute lymphoblastic leukemia (ALL) cell line, designated LC4‐1, was established from peripheral blood mononuclear cells of a patient with acute non‐T‐cell ALL. LC4‐1 cells were characteristically positive for Ia, B4, and common ALL antigens (CALLA), but negative for B2, Tac, T3, T4, T8, T11, and M1 antigens and E‐rosette formation. Approximately 30% of LC4‐1 cells expressed detectable amounts of B1 antigens. LC4‐1 cells expressed neither Epstein‐Barr‐virus–associated nuclear antigen (EBNA), cytoplasmic immunoglobulins (cIg) nor surface immunoglobulins (sIg). Gene rearrangements had already occurred in LC4‐1 in the D‐J region of immunoglobulin heavy chain genes, but not in T‐cell receptor (β‐chain) genes, suggesting that LC4‐1 is a progenitor cell line of B‐cell lineage earlier than pre‐B‐cells. The expression of cell surface antigens of LC4‐1 was changed by treatment with 4‐phorbol 12‐myristate 13‐acetate (PMA) (0.1 ng/ml) for 2 days. Before treatment with PMA, about 98% of LC4‐1 cells were positive for B4, CALLA, and Ia. However, following treatment they lost CALLA expression without any change in expression of Ia and B4. There was no change in B1‐positive population. The change in surface antigens on LC4‐1 cells seems to be due to differentiation induced in the cells by PMA. These results support the hypothesis that CALLA is a differentiation antigen and suggest one possible differentiation pathway for pre‐B‐cells.