Influence of protein deficiency on immune response to sheep red blood cells was investigated in rats and mice with Jerne's plaque-forming cell technique. Protein deficiency resulted in a reduction in the number of antibody-producing cells consequent upon a prolongation of cell generation time in rats. Injection of syngeneic thymocytes brings about better improvement in the immune response of the X-radiated protein-deficient mice as compared to the controls. It is suggested that depressed immunity in malnutrition may be partly due to a disturbance in thymic function
