TNF and asthma: As anticipated, the asthma (+) group also exhibited defective NK-cell production of IFN-γ (P<0.005 against 221; P<0.05 against K562) and TNF-α (P<0.05 against 221) relative to the control group; this difference was less pronounced in the asthma (−) group (P<0.005 vs. P<0.05 against 221 for IFN-γ production) (Fig. 4A).