The primary and secondary immune responses to sheep red blood cells (SRBC) were profoundly depressed in rats with malnutrition as determined by the marked reduction of direct plaque- (PFC) and rosette- (RFC) forming cells in the spleen, thymus and bone marrow.
In the thymus and spleen of the immunized rats with malnutrition during the primary immune response the percentage reduction of RFC was greater than that of PFC but in the secondary immune response it was the reverse that occurred.
Skin transplants were rejected by rats with malnutrition as they were in the controls although it is possible that transplants would survive longer in more severely malnourished animals.
Peripheral blood lymphocytes from both unimmunized rats and monkeys with malnutrition responded better to pokeweed mitogen (PWM) than to phytohaemag-glutinin (PHA), suggesting greater impairment of thymus-derived dependent T cells, than of bursa equivalent, antibody-forming B cells among peripheral blood lymphocytes. In the control animals the PHA responsiveness was greater than PWM responsiveness.