Up-regulation of natural killer cell cytotoxicity by interleukin-2: The effect of sex and parity

PROBLEM: Peripheral blood lymphocytes (PBLs) from some, but not all, female donors showed increased cytotoxicity in response to interleukin (IL)-2. METHOD OF STUDY: The effect of IL-2 on natural killer (NK) cell cytotoxicit y was compared in nulliparous females, parous females, and males. Periphera l blood lymphocytes were preincubated for 20 or 72 hr with 5 or 100 U/ml IL -2 and cytotoxicity against K562 targets was then examined. RESULTS: In the parous females, only the 72-hr preincubation with 100 U/ml IL-2 significantly increased NK cell cytotoxicity, whereas nulliparous fema les also showed significantly increased cytotoxicity after a 20-hr preincub ation with 100 U/ml IL-2. Neither female subject group had increased activi ty after preincubation for 20 or 72 hr with 5 U/ml IL-2. However, male peri pheral blood lymphocytes also showed a significant increase in NK cell cyto toxicity when preincubated for 72 hr with 5 U/ml IL-2. CONCLUSIONS: The effect of IL-2 on NK cell cytotoxic activity may be relate d to sex and the state of parity.