increases proliferation of cytotoxic T cells. and enhances rejection of skin grafts in mice (5). Similar data from humans were also seen: a low-carotenoid diet led to decreased delayed-type skin hypersensitivity reactions (mediated by T cells) and supplementation with B-carotene restored the skin reactions to normal [6] Although a variety of cell-based mechanisms that do not involve eicosanoids have been proposed for modulating the immune response, perhaps some of the strongest evidence comes from studies of general nutritional status. Both overmutri- tion and energy restriction have profound effects on the immune system's regulation Overnutrition that results in obesity depresses the immune response. while energy restriction that avoids nutrient deficiencies enhances the immune response. particu- larly in older animals 17]