Nutritional Deficiencies and Intestinal Mucosal Immunity

Publisher Summary This chapter focuses on nutritional deficiencies and intestinal mucosal immunity. Protein-energy malnutrition (PEM) results in an increased risk of gastrointestinal infection. This can be attributed in part to impaired immune responses. Systemic cell-mediated immunity is decreased as judged by reduced number and function of thymus-dependent lymphocytes, impaired delayed cutaneous hypersensitivity reactions, and decreased production of lymphokines. Concentration of secretory immunoglobulin A (IgA) is reduced and there are fewer intraepithelial lymphocytes. Antibody responses following viral vaccine administration are reduced and there is a decrease in natural killer cell activity. In addition, the number of bacteria binding to epithelial cells is increased. These changes are also observed in certain selected nutrient deficiencies, such as that of vitamin A. Epidemiological studies have documented the adverse effect of PEM on morbidity and mortality. Pathological examination of tissues from children dying of PEM showed the frequent presence of several opportunistic microorganisms, including Pneumocystis carinii .