Differential effects of stimulatory factors on natural killer cell activities of young and aged mice.

Age-associated influences on natural killer (NK) cell functions following cytokine stimulation were examined in splenocytes from C57BL/6 mice. NK cells of both young and aged mice exhibited significantly increased: interferon-γ production after interleukin (IL)-12 or IL-15 alone or any combination of IL-12, IL-18, and IL-2; cytotoxicity after IL-2 or IL-15; and granzyme B expression after IL-15. The only significant age-associated differences were observed in interferon-γ production after IL-15 or IL-12 + 18 + 2 and in granzyme B expression following IL-2 or IL-15. Perforin expression did not increase following stimulation; however, NK cells from aged mice expressed significantly higher levels than young mice. These results underscore the complexity of the cytokine-induced functional activities of NK cells and illustrate the differential response of NK cells from young and aged mice to cytokine stimulation.