Gene Dose Effects in Ir Gene-Controlled Systems

(B10.A × B10.S)F₁ hybrid mice produce lower levels of anti-GLφ 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) × B10.S(8R)]F₁ mice were immunized with GLφ. 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 × B10.S) and [B10.S(9R) × 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 GLφ controlled by complementary Ir genes.