IL17A and major depressive disorder: • Higher concentration and ex vivo production of IL-6 (moderating effect of comorbid major depressive disorder; mostly from studies in adults)¶ • Higher concentration of IL-1β (only in drug-naïve patients; mostly from studies in adults)¶ • Higher concentration of IL-2, IL-8, IL-17, soluble TNFR 1 and 2, CCL3 and CXCL8 (adults)# • Covariation of TNF-α and IL-12 plasma levels and tic/OCS severity# • Higher concentration of IL-1β, MCP-1 and IP-10 in patients with acute exacerbation of OCS requiring hospitalization#