The liver is the major site of clearance and degradation of foreign antigens from the portal circulation. Despite the presence of hepatic accessory cells, antibody responses to orally administered antigens are uncommon. To ascertain if hepatic accessory cells are incapable of stimulating specific subsets of T lymphocytes, freshly isolated hepatic nonparenchymal and splenic cells were cultured with a panel of antigen-specific, H-2-restricted Th1 and Th2 HTL clones. Whereas spleen cells stimulated the proliferation of both Th1 and Th2 clones, hepatic nonparenchymal cells (NPC) stimulated the proliferation of only Th1 and not Th2 clones. Adding rIL-1, rIL-6, and rIL-7, alone or in combination, to the cultures did not result in proliferation of the Th2 clones. Despite the absence of Th2 proliferation, NPC were able to stimulate the secretion of IL-3 and IL-4 by Th2 clones in the presence of antigen. Moreover, adding hepatic NPC did not inhibit spleen cells from stimulating Th2 clones in the presence of antigen. Thus, the inability of liver cells to stimulate the proliferation of Th2 helper T lymphocytes appears to be secondary to an absence of either an unknown accessory cell cofactor or an accessory cell that preferentially presents antigen to Th2 cells. The selective activation of Th1 and not Th2 cells by liver accessory cells may result in suppression of antibody responses to orally administered antigens.