Adherent cell requirement for the effect of vitamin E on in vitro antibody synthesis

Mice deficient in dietary vitamin E are impaired in their humoral and cell-mediated immunological responses. The basis for this impaired immunocompetence was investigated by using the in vitro antibody response as an assay system. Spleen cells from mice fed vitamin E-deficient diets were low responders to the antigens, sheep red blood cells (SRBC) and dinitrophenyl-L-lysine-Ficoll (DNP-Ficoll). However, they responded as well as mice fed vitamin E-supplemented diets to the relatively macrophage-independent antigen trinitrophenylated-lipopolysaccharide (TNP-LPS). This suggested that the macrophage was the cell most affected by the vitamin E deficiency. The involvement of macrophages was confirmed directly by mixing experiments, in which it was shown that macrophages from vitamin E-deficient mice were unable to support an antibody response by macrophage-depleted spleen cells from vitamin E-supplemented mice. Macrophages from vitamin E-deficient mice expressed less Ia antigen, and seemed less able to present antigen to nonadherent cells. However, it was found that macrophages from vitamin E-deficient mice not only lacked accessory cell function, but could act instead as suppressor cells. The effect of dietary vitamin E was noted with either saturated or unsaturated sources of fat in the diet.