CD8A and major depressive disorder: The number of resting NK cells (p < 0.01), monocytes (p < 0.01) and M0 macrophages (p < 0.01) was increased in MDD patients, while the other immune cell types, including CD8+ T cells (p < 0.05) and gamma delta T cells (p < 0.001), were decreased (Figures 1A,B, Supplementary Table S1).