Natural killer cell activity associated with aging and sex in humans

The effect of aging and sex on natural killer (NK) cell activity in humans was investigated. The results showed that there were no significant differences in both the age- and sex-related NK cell activities with or without polyinosinic acid-polycytidylic acid stimulation. On the other hand, the mitogenic response of peripheral blood lymphocytes in the aged group (aged 70 to 86 years) was found to be significantly depressed in compared with that in the young adult group (aged 20 to 30 years). These data suggest that the NK cell activity of the aged subjects is operative, and may be important in defense against neoplasia since extensive immunodeficiencies are known to be associated with aging.