Monokine secretion in aging and protein malnutrition.

Aged and protein-malnourished hosts have diminished febrile responses and increased morbidity and mortality from infection that could be due to deficiencies in the production of certain monokines. In this study, the ability of peritoneal macrophages from aged and protein-malnourished rats to produce IL-1 and TNF was explored. Aged rats fed a standard diet produced less IL-1 and TNF, as measured by the thymocyte proliferation and L929 cytotoxicity assays, than young and middle-aged rats. Monokine production was not diminished by protein malnutrition in any age group. No synergistic decline in IL-1 or TNF production was seen with increasing age in malnourished rats. Diminished IL-1 and TNF production may partially explain the severity of infection seen in the elderly patient, but not the malnourished host. The role of other cytokines such as IL-6 and cytokine inhibitors in aging and malnutrition should be explored.