Effect of a low-protein diet on the immune system in mice

The effect of an 8% casein diet (low-protein diet, LPD) on the immune system in, mice was compared with that of a 27% casein diet (control diet, CD). Serum protein level, body weight gain and DTH responses to Listeria monocytogenes (L.M) were suppressed in LPD-fed mice. Primary plaqueforming cell (PFC) responses to SRBC in LPD-fed mice remained low because of suppression of an increase in spleen cell number. There was no effect on natural killer cell activity. A low level of phagocytosis of E. coli B by peritoneal macrophages was observed in LPD-fed mice. The mortality of LPD-fed mice due to primary infection with E. coli B or L.M was slightly lower than that of CD-fed mice, but higher in secondary infection with L.M. These results demonstrate a relationship between undernutrition produced by a low-protein diet and some aspects of the immune system in mice.