The induction of Leu-1 antigen expression in human malignant and normal B cells by phorbol myristic acetate (PMA).

Malignant cells from five patients with B cell leukemia or lymphoma were cultured with phorbol myristic acetate (PMA). PMA was found to induce cell surface expression of the Leu-1 antigen in cells from three of the five patients. Using one- and two-color immunofluorescence staining and flow cytometry, we have shown simultaneous expression of the Leu-1 antigen with other B cell markers. Induction of Leu-1 antigen expression was not related to histologic subtype, in vitro secretion of immunoglobulin, or other clinical features. Biosynthetic labeling experiments showed that synthesis of Leu-1 antigen occurred and preceded expression of the antigen on the cell surface. PMA also induced the appearance of Leu-1 antigen-positive B cells in cultures of normal peripheral blood mononuclear cells. We propose that the Leu-1 antigen is expressed transiently during the differentiation of some B cells.