The characterization of a human B cell line utilizable for the assay of B cell growth factors.

An EBV-transformed B cell line JR-2(82) is described which proliferates in response to human B cell growth factor (BCGF) preparations. Although spontaneous replication occurs at high cell densities, at cell densities of 10(3) cells or less, cell death occurs in the absence of BCGF. This response is not dependent upon the presence of low concentrations of supplemental serum in the culture medium. There is no proliferative response to various preparations of interleukin (IL)-1, IL-2 or gamma-interferon (gamma-IFN) up to 1000 U/ml either alone or in combination and specific antisera to IL-2 and gamma-IFN do not interfere with the proliferative response. At 5000 U/ml of gamma-IFN or greater, a partial proliferation of the line is seen to 30% of maximal. The JR-2(82) line and its clones appear to proliferate preferentially in response to low molecular weight (LMW) BCGF, compared to the response seen to high molecular weight (HMW) BCGF from Namalwa cell line supernatants. The line does not produce Ig spontaneously but on incubation with B cell differentiation factor (BCDF) containing supernatants differentiates to an IgG-producing cell line. JR-2(82) or its derivatives may therefore provide a simple reproducible assay for BCGF in the presence of other lymphokines and may be used to study further the interactions of lymphokines in the regulation of the proliferation of EBV-transformed cells.