Malnutrition and immunological function with special reference to cell-mediated immunity

Malnutrition, and especially undernutrition, is the most common cause of acquired immune dysfunction worldwide. Establishing a cause-effect relationship among nutritional variables, immunological function, and disease susceptibility has proved to be difficult. In this review, the degree to which macronutrient and micronutrient deficiencies affect cell-mediated immunity and immunoregulation is discussed. The evidence for malnutrition-immune response linkages is grouped according to in vitro studies of thymus gland morphology and function, peripheral T-lymphocyte number and responsiveness to antigens, and soluble immunoregulatory mediators, and in vivo studies of delayed hypersensitivity, graft rejection, and cytotoxicty. Limitations of these studies are considered in light of disease resistance/susceptibility to pathogens that evoke cell-mediated immune responses.