Induction of Proliferation of B Prolymphocytic Leukemia Cells by Phorbol Ester and Native or Recombinant Interferon-γ

Abstract

AbstractPhorbol ester phorbol myristate acetate (PMA) induces proliferation in nonmalignant human B cells and B cells from a patient with B prolymphocytic leukemia (B-PLL). Mitogen-free T cell-derived conditioned medium acts synergistically with PMA in inducing proliferation of B-PLL cells but does not enhance the PMA-stimulated outgrowth of nonmalignant B cells. Interleukin 2 (IL-2) has no effect on the outgrowth of B-PLL cells, and monoclonal antibodies against the IL-2 receptor do not influence the response to PMA and conditioned medium. Recombinant interferon-γ (IFN-7), in contrast, is a potent enhancer of PMA-induced proliferation of B-PLL cells. With gel filtration techniques and with the use of anti-IFN-γ antibodies, it is shown that IFN-γ in the conditioned medium is responsible for the observed increase in B-PLL cell proliferation. Preincubation of B-PLL cells with IFN-7 induces responsiveness to PMA, whereas IFN-7 alone had no effect on these cells when pretreated with PMA. The combined data show that, in the presence of PMA, native and recombinant IFN-7 are growth factors for B cells from a B-PLL patient and that IL-2 is not involved in this process.© 1987 by Grune & Stratton, Inc. 0006-4971/87/7003-0010$3.00/0