[The immunity of senescence. Study of lymphocytes in vitro. I: Rosette forming lymphocytes].

E and EAC rosettes forming lymphocytes were evaluated in 25 elderly subjects (mean age 84.76 years) without manifestations of neoplastic or infectious diseases. The percentage of E rosettes appeared within the normal range in about 50 per cent of cases and below normal in remaining 50 per cent. No evident sex-related differences were observed. The percentage of EAC rosettes showed a larger distribution of values. In fact, 56 per cent of cases fell within normal limits, 26 per cent was higher and 20 per cent lower than normal. Our results are in agreement with the data reported in the most recent literature, which indicates that the main target of immune system senescence is the T-cell population, while B cells do not show significant age-related variations. The significant number of cases with percentages of EAC rosettes higher than normal may be attributed to the failure of immune homeostatic mechanisms normally exerted by T cell subpopulations. Further studies on several immune system functions in advanced age are in progress.