[Higher production of tumor necrosis factor (TNF) elicited by a biological response modifier (BRM) in aging mice]

We investigated age-related changes in the capacity for tumor necrosis factor (TNF) production in young and aged inbred C3H/He mice by injecting them with OK-432, a biological response modifier (BRM). An intravenous injection of 0.4mg of OK-432 was found to induce TNF production and two consecutive injections of 2KE of OK-432 induced much higher TNF production. Both the single and two consecutive injections of OK-432 induced significantly higher TNF production in aged mice than in young ones. Furthermore, the TNF-productive response to the two consecutive injections of OK-432 seemed to increase with aging. Male mice tended to show a marginally higher TNF-productive response than females. The mechanism by which aged mice have a higher capacity for TNF production is not clear. The following possibilities are conceivable. 1) Macrophages which are major TNF producer cells may be activated in aged mice. 2) Specific T cells which are cross-reactive to antigenic determinants in OK-432 may be increased in number in aging mice and activate macrophages effectively to produce TNF when stimulated by OK-432. In general, immunological functions tend to decline with aging. Our present results, however, suggest that by using an appropriate BRM we may be able to induce higher TNF production in the aged. This might lead to effective prevention and therapy for tumors, which increase in incidence with age.