Haplotype preference in lymphocyte differentiation. II. F1 hybrid helper T cells generated with antigen-bearing parental macrophages can cooperate with B lymphocytes of either parent.

Carrier-specific helper T cells were generated in F₁ hybrid mice by either conventional immunization procedures or by repeated immunizations with antigen-bearing macrophages derived from either F₁ or parental donors. The F₁ helper T cells generated in these various ways were then analyzed for their capacities to help hapten-primed B lymphocytes derived from each of the two parental strains as well as from F₁ donors in the development of secondary anti-hapten antibody responses. These analyses were conducted using two different types of in vivo assay systems as well as a totally in vitro system. Under all circumstances, helper T cells from F₁ mice, primed either in conventional fashion or with antigen bearing parental or F₁ macrophages, were capable of interacting effectively with B lymphocytes of each parent and of F₁ origin. Moreover, in the case of F₁ helper cells primed with antigen-bearing parental macrophages, there was no evidence of preferential helper activity for parental B lymphocytes corresponding to the type of macrophage used for sensitization; this was true irrespective of whether in vivo or in vitro assay systems were employed. The relevance of these findings and others which are either similar to, or discordant with, them to the general question of genetic restrictions in macrophage-T lymphocyte interactions is discussed.