Restricted helper function of F1 leads to parent bone marrow chimeras controlled by K-end of H-2 complex

F1 leads to parent bone marrow chimeras were prepared by transferring F1 hybrid marrow cells into heavily irradiated parental strain mice. When unprimed, donor-derived F1 T cells from the chimeras were activated to sheep erythrocytes (SRC) for 5 days in irradiated normal F1 mice, high IgM and IgG anti-SRC responses were observed with F1 B cells, and with B cells H-2-compatible with the strain in which the T cells were raised from stem cells. Significantly, however, responses with B cells of the opposite parental strain were either absent or very low. The restriction in T-helper function mapped to the K-end of the H-2 complex and could not be attributed to active suppression.