Lymphokine-induced IgM secretion by clones of neoplastic B cells

The induction of antibody secretion by B cells requires T-cell-derived factors. Such factors have been described but the precise relationship among these various factors is not clear, and it has been difficult to demonstrate that these factors act directly on the B cell and do not exert their effect via T cells or macrophages. In this report we describe the direct induction of IgM synthesis and secretion in cloned lines of long-term tissue culture adapted neoplastic B cells (BCL) by T-cell super-natants from phorbol-12-myristate 13-acetate (PMA)-induced EL-4 cells or concanavalin A (Con A)-induced 7.1.1a cells. We have termed this activity BCDFμ (B-cell differentiation factor for IgM). The supernatants containing BCDFμ induce activated and neoplastic B cells to secrete IgM and the factor responsible is distinct from BCGF, interleukin-2 (IL-2), the classical T-cell replacing factor (TRF) described by Schimpl and Wecker, and immune interferem (IFNγ). © 1983 Nature Publishing Group.