Analyzing the whole population together, IL‐2 production was inversely correlated with FEV1 (r = −0.558, P = 0.0162; Figure 1A) and positively correlated with total daily dose of inhaled corticosteroid (r = 0.561, P = 0.0155; Figure 1B), suggesting its association with asthma severity. Here, IL2 is linked to asthma.