INFLUENCE OF AGING ON SOME SPECIFIC AND NONSPECIFIC MECHANISMS OF THEHOST-DEFENSE SYSTEM IN 146 HEALTHY-SUBJECTS

The influence of aging on some parameters of systemic host defense mec hanisms, i.e. white cell counts, lymphocyte subpopulations, delayed-ty pe hypersensitivity (DTH), polymorphonuclear and mononuclear leukocyte functions, was evaluated. One hundred and forty-six healthy volunteer s (60 men and 86 women), aged 25-100 years, were enrolled. None of the subjects had taken any drug in the month before the study. Subjects w ere divided into three age groups: 25-45, 46-65 and 66-100 years. Grou ps were comparable in size, and sex distribution was similar throughou t all age groups. Elderly people were 51 healthy volunteers between th e ages of 66 and 100 years (mean age 79.2). Younger people were 41 sub jects between the ages of 46 and 65 years (mean age 54.3) and 53 betwe en the ages of 25 and 45 years (mean age 32.7). As for the comparison between sexes, no significant differences in the values of the studied parameters were found between males and females (p > 0.05). Only quan titative DTH data, i.e. the number of antigens producing positive reac tions and the score (sum of positive reaction diameters), were signifi cantly (p < 0.05) reduced in responsive females when compared to males . Aging did not affect white cell counts, lymphocyte subsets and many phagocytic functions, i.e. phagocytosis frequency and index, nitroblue tetrazolium reduction, superoxide production, microbicidal activity a gainst bacteria and yeasts. A significant decrease (p < 0.05) in the c hemotactic response to serum-derived chemotactic factors was observed in aged people in comparison to younger subjects. Anergy was more freq uent in older (about 29%) than in younger (5-9.4%) healthy volunteers. Among the responsive population, the number of antigens producing pos itive reactions was superposable in the three age groups while the DTH score was significantly (p < 0.05) increased in the elderly. Results of the study suggest that aging is responsible only for minor changes in many important mechanisms of the defense system in healthy individu als.