Evidence for Ir Gene Expression in the Antigen-Presenting Cell

Proliferative responses by peritoneal exudate T-lymphocyteenriched cells (PETLES) from GAT primed mice can be stimulated by GAT-pulsed spleen cells from non-immune animals only if the donors of both cell types are identical at the I-A subregion of the major histocompatibility complex (MHC). However, in 4 separate (high responder × low responder)F₁ strains, GAT-primed PETLES could be stimulated by GAT/presenting cells from either the F₁ or the high responder parent but not by cells from the low responder parent. Addition of equal numbers of GAT-pulsed low responder spleen cells did not affect the response of F₁ PETLES to GAT on high responder spleen cells. Furthermore, pre-treatment of F₁ PETLES with anti-Ly 2.2 serum and complement did not allow these cells to respond to GAT-pulsed low responder parental spleen cells. This suggests that the failure of spleen cells from low responder parental strains to present GAT to F₁ PETLES is not due to the presence of suppressor cells in either the antigen-presenting or the responding cell populations.