Immune function and survival in a long-lived mouse strain subjected to undernutrition.

Functional immune changes were monitored in populations of the long-lived C57BL/6J strain of mice which were subjected to dietary restriction from time of weaning or subjected to such restriction both before and after weaning, along with the appropriate control populations. Responses to T and B cell mitogens (PHA, Con-A, pokeweed, bacterial lipopolysaccharide, and PPD), to injected sheep red blood cells, and measurement of skin allograft rejection rates were followed. Early in life, restricted mice appear immunosuppressed, as judged by all these parameters. Skin allograft rejection remained suppressed until relatively late in life. Other responses tended to reverse from the earlier pattern; by mid-life restricted mice responded better than controls. Dietary restriction profoundly affects the immune system. Mice on such regimes display anatomic and certain immune functional changes which suggest that the immune system may mature less rapidly and stay "younger" longer than in the controls. Furthermore, dietary restriction results in prolongation of life span.