Nutritional influences on immune response in healthy aged persons.

Healthy elderly (80+/-5 years) with different nutritional status were compared to young healthy adults (25+/-5 years) to quantify the relative influences of aging and nutrition on immune response. Aged persons, without alteration of their nutritional status, had lower CD3+, CD8+, and CD45RA+ as well as higher CD2+CD3-, CD2+CD4-CD8-, and CD45RO+ T cell subsets and IL-6 release than their younger counterparts. T cell proliferation and IL-2 production were comparable in the two healthiest groups. Aged subjects with low nutritional status expressed similar but more marked changes in immune response while nutritional status did not influence the immune response in young subjects. Furthermore, lower nutritional status was associated with lower CD4+ counts and lower T cell functions in aged persons. These results indicate that the influences of aging and undernutrition in humans are cumulative and suggest that some changes in immune response that have been attributed to aging may, in fact, be related to nutrition and not aging.