B cell growth factors and B cell differentiation factor from human T hybridomas. Two distinct kinds of B cell growth factor and their synergism in B cell proliferation.

Abstract

Human T hybridomas secreting B cell growth factors (BCGF) and B cell differentiation factor (BCDF) were established. Hybrid clones 77-A, 94-C and 98-F secreted BCGF that induced proliferation of anti-IgM-stimulated normal B cells. The culture supernatant from 77-A cells could also maintain continuous proliferation of colony-forming B cells, but the factor from 94-C could not. The addition of the supernatant from 94-C cells to that from 77-A cells synergistically augmented the proliferation of colony-forming B cells, demonstrating the existence of 2 distinct kinds of BCGF and the synergism between them. These supernatants showed no interleukin 2 (IL-2) or BCDF activity. A hybrid clone, 90-E, secreted BCDF. The culture supernatant induced Ig production in Cowan I-stimulated normal B cells or in a [Epstein-Barr virus] transformed B cell line, CESS. The supernatant had no BCGF or IL-2 activity. Anti-Ig-stimulated B cells, but not IL-2-dependent T cells absorbed BCGF activity, and CESS cells absorbed BCDF activity, but not BCGF activity, in the culture supernatants from T hybridomas. IL-2, BCGF and BCDF were different molecules, and acceptors specific for each molecule were present on each target cell.