Functional requirements of (Phe, G)-A--L-specific T-cell clones of (H-2b X H-2k)F1 origin.

T-cell clones specific for the synthetic polypeptide antigen poly(LPhe, LGlu)-poly(DLAla)--poly(LLys) of (C57BL/6 X C3H/HeJ)F1 origin were tested for their biological activities. One group of clones was restricted in its proliferative response to the H-2b haplotype, the second to the H-2k haplotype, and the third to the F1 unique Ia determinants. All the clones which proliferated in response to antigen secreted interleukin-2 (IL-2) following stimulation. The H-2 restriction of the IL-2 secretion was the same as that of the proliferation. Two of the clones tested, C.6 and C.10, could provide help to B cells in antibody production. However, the genetic restriction profile of the helper activity was less stringent than that for the proliferative response. Thus, C.6, which proliferated in the presence of F1 antigen-presenting cells only, could help B cells and accessory cells of C3H/HeJ. C.10, which was restricted in its proliferative response to the H-2b haplotype, could collaborate with B cells and accessory cells of the H-2k haplotype as well. The antibody response of both clones was restricted to the parental or F1 strains.