GAD patients displayed markedly higher serum levels of IL-2 (14.81 ± 2.88 pg/ml) compared to HCs (8.08 ± 1.10 pg/ml), and the difference reached the statistically significant level (p = 0.037, two-tailed unpaired t-test) (Table 2; Fig. 1). Here, IL2 is linked to generalized anxiety disorder.