Human B lymphoblastoid cell lines provide an interleukin 1-like signal for mitogen-treated T lymphocytes via direct cell contact.

The B lymphoblastoid cell lines (B-LCL) 8392, SB, 1788, and Daudi provide accessory cell activity for mitogen-treated T cells, whereas the T lines MOLT-4, 8402, CEM, and HSB do not provide this function. Direct cell contact is required for the accessory cell activity, and active lymphocyte growth factors could not be detected in the supernatants of the B-LCL. The B-LCL also present alloantigens to responding T cells, and this response is independent of additional accessory cells. The target for the B-LCL is the responding T cell itself, rather than a minor contaminating population of endogenous accessory cells. This conclusion is based on the finding that, under culture conditions in which T cells do not proliferate in response to PHA, accessory cell activity of the B-LCL is maintained. Paraformaldehyde- or glutaraldehyde-treated B-LCL retain their accessory cell activity at levels of these agents that completely eliminate metabolic activity of the B-LCL, as determined by incorporation of leucine, thymidine, and uridine into macromolecules. This treatment eliminates alloantigen presentation by the B-LCL. T cells treated with IO-4 or with monoclonal anti-T3 antibodies fail to respond to highly purified IL 1, and respond minimally to supra-optimal concentrations of IL 2. Nevertheless, these cells respond maximally to the accessory cell activity of the B-LCL. The IO-4 treated cells or cells exposed to anti-T3 also proliferate in response to TPA. Together, our data suggest that the B-LCL provide an IL 1-like signal for mitogen-treated T cells via direct cell contact, in the absence of detectable soluble IL 1.