Abstract
Many cytokines have been documented to have a multiplicity of biological effects by acting on a variety of cells. In order to determine whether human BCGF-II acts on any cells in addition to normal B cells, the effect of human BCGF-II on murine thymocytes, human peripheral blood T cells, a human natural killer-like cell line, YT, and Epstein-Barr virus (EBV)-transformed B-cell lines was further examined. BCGF-II augmented incorporation of [ 3H]thymidine by murine thymocytes in combination with suboptimal doses (0.5 μg/ml) of concanavalin A (Con A) but not at lower doses (0.1 μg/ml) of Con A, a concentration usually used for interleukin 1 (IL-1) assays. BCGF-II could not induce proliferation or Tac antigen (Ag) expression on normal peripheral blood T cells stimulated with OKT3 antibody. Both proliferation and Tac Ag expression on YT cells were also augmented by BCGF-II. BCGF-II induced both high- and low-affinity IL-2 receptor (IL-2R) on YT cells as determined by 125I-IL-2-binding assay. Two of seven EBV-transformed B-cell lines tested (ORSON and AUM cells) in response to BCGF-II exhibited augmentation of proliferation and cell surface Tac Ag expression. BCGF-II in the presence of low doses (0.1 μg/ml) of phorbol myristate acetate (PMA) also induced Tac Ag mRNA (3.5 and 1.5 kb) in these B-cell lines. The IL-2R induced on these B-cell lines, however, consisted mostly of low-affinity receptors. Both Tac Ag and its mRNA in these B-cell lines were not induced by Forskolin but by PMA, suggesting that this induction may involve protein kinase C. The present study shows that human BCGF-II can stimulate YT cells, murine thymocytes, and some EBV-transformed B-cell lines but not peripheral blood T cells. Consequently, BCGF-II can induce the growth and differentiation of a number of cell types in addition to normal B cells.
Published Version
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