In vitro analysis of allogeneic lymphocyte interaction. III. Generation of a helper allogeneic effect factor (AEF) across an I-J subregion disparity.

Allogeneic effect factors (AEF) were produced across an I-J subregion incompatibility. The helper activity of these AEFs is H-2 restricted since they help B cells only of the stimulator haplotype and of other haplotypes that carry the same I-J subregion gene(s) as the stimulator haplotype. Immunoadsorption studies demonstrate that they consist of I-J determinants derived initially from the GVHR host and MLR stimulator cells and not the GVHR donor and MLR responder cells used to generate AEF. It is postulated that the genetic restriction of AEF helper activity is mediated in part by the ability of the GVHR activated donor T cells to acquire, in vivo, recipient T cell and/or macrophage derived I-J determinants. Cellular adsorption studies indicate that AEF helper activity may be adsorbed by B cells, but neither T cells nor macrophages, of the stimulator haplotype. The results suggest that an I-J-positive AEF interacts with an I-J subregion controlled complementary recognition structure on a target B cell and, after antigenic stimulation, activates that B cell to IgG antibody synthesis.