CXCL8 and major depressive disorder: In the MDD group, a strong positive correlation was observed between iSC Hi CD4 T cells and mRNA expression of IL-5 (Rho = 0.94, p = 0.015), IL-8 (Rho = 0.65, p = 0.033), IL-13 (Rho = 0.70, p = 0.019), and CCL-2 (Rho = 0.80, p = 0.001).