The development and nature of immune deficit in primates in response to malnutrition.

Within 2--3 days of establishing protein-energy malnutrition (PEM) in primates there was a significant reduction (P less than 0.01) of the serum transferrin and C3 concentrations. No such changes occurred in the serum albumin until 21 days later. There was an early marked development of immune deficiency, at least 3 weeks before any signs of infection. Lymphocyte E and EAC rosetting, DNA stimulation, in vivo delayed hypersensitivity, passive cutaneous anaphylaxis and skin-graft rejection were all markedly decreased as early as Day 7 of the restricted diet. There was a disproportionately high percentage of null cells, especially in the spleen and bone marrow. The same types of organisms were grown from cultures of conjunctival and throat swabs of control and malnourished animals. Four weeks after the primates had been on their respective diets, a higher number of coagulase-negative staphylococci were isolated from blood cultures of the most severely malnourished baboons. Serum C-reactive protein was negative and the IgG concentration remained at virtually the same level throughout. Extensive histopathological examination and culture revealed no infection in lungs, spleen, lymph nodes or liver. These results clearly indicate that severe immunosuppression in PEM may occur long before the onset, and in the absence of, any infection.