TGFB1 and major depressive disorder: Furthermore, we were unable to perform analyses of other cytokines and chemokines underrepresented in pediatric research that have been identified in the literature to be empirically associated with depression (e.g., IL-13, IL-12) or immunologically important (e.g., IL-1, IL-2, IL-4, IL-5, TGF-β, see Himmerich et al., 2019).