IL17A and major depressive disorder: However, the IL-17 levels (MDD, 21.55 ± 17.70 pg/mL, vs. male HC, 6.755 ± 7.536 pg/mL, p = 0.0039; vs. female HC, p = 0.0416; Figure 2D) in the serum significantly increased in young adult male patients with MDD compared with those in the male and female HC groups.