Ageing modulates some aspects of the non-specific immune response of murine macrophages and lymphocytes

The deterioration of the immune system with ageing, which leads to an incre ased morbidity and mortality from infections, appears to be related to decr eases in specific lymphocyte functions. However, the alteration of non-spec ific immunity is a more controversial subject. Our purpose was to investiga te the age-related changes of different functions of the non-specific immun e response in peritoneal macrophages (adherence to tissues, mobility direct ed to a chemical gradient from an infectious focus or chemotaxis, phagocyto sis of foreign agents and destruction of these agents by superoxide anion p roduction) and in lymphocytes (adherence and chemotaxis) from peritoneum, a xillary lymph nodes, spleen and thymus. We used young (12 weeks), adult (22 weeks), mature (48 weeks) and old (72 weeks) female BALB/c mice. The adher ence capacity of macrophages and lymphocytes was greater in adult and old m ice than in young animals. The chemotaxis of macrophages showed higher valu es in cells from young mice than in those from adult mice, increasing again in macrophages from mature and old animals. A similar behaviour was shown by phagocytosis, which reached its highest values in old animals. Anion sup eroxide production increased with age and again the highest values were obt ained in the oldest mice. Conversely, chemotaxis of lymphocytes was higher in the adult and mature animals than in the young and old animals. We concl ude that, although there is a decrease in lymphocyte chemotaxis in old anim als, the non-specific immune response of macrophages instead of decreasing, may increase in aged mice with respect to the values seen in adult mice.