Influence of aging on some specific and nonspecific mechanisms of the host defense system in 146 healthy subjects.

The influence of aging on some parameters of systemic host defense mechanisms, i.e. white cell counts, lymphocyte subpopulations, delayed-type hypersensitivity (DTH), polymorphonuclear and mononuclear leukocyte functions, was evaluated. One hundred and forty-six healthy volunteers (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 were divided into three age groups: 25-45, 46-65 and 66-100 years. Groups were comparable in size, and sex distribution was similar throughout all age groups. Elderly people were 51 healthy volunteers between the ages of 66 and 100 years (mean age 79.2). Younger people were 41 subjects between the ages of 46 and 65 years (mean age 54.3) and 53 between 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 quantitative DTH data, i.e. the number of antigens producing positive reactions and the score (sum of positive reaction diameters), were significantly (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 against bacteria and yeasts. A significant decrease (p < 0.05) in the chemotactic response to serum-derived chemotactic factors was observed in aged people in comparison to younger subjects. Anergy was more frequent in older (about 29%) than in younger (5-9.4%) healthy volunteers.(ABSTRACT TRUNCATED AT 250 WORDS)