Gene dose effects in Ir gene-controlled systems.

(B10.A x B10.S)F1 hybrid mice produce lower levels of anti-GL phi antibody than B10.S(9R) and B10.HTT mice. To determine whether this difference is due to a gene dose or a cis-trans effect, [B10.S(9R) x B10.S(8R)]F1 mice were immunized with GL phi. These mice carry one dose of the responder Ir gene alleles in the cis position whereas the recombinant B10.S(9R) and B10.HTT mice carry two doses of the relevant genes. Both (B10.A x B10.S) and [B10.S(9R) x B10.S(8R)] F1 mice produced comparably lower amounts of antibodies as compared to the recombinant strains. The data therefore demonstrate that gene dose and not cis-trans effect accounts for the differences between F1 and recombinant strains in their antibody response to GL phi controlled by complementary Ir genes.