Evidence deriving from genetic, neuropathological, cerebrospinal fluid, and serum studies in humans with MDD and from animal models of depressive-like behavior and chronic stress reveal numerous neuroinflammatory abnormalities in MDD, including [4]: (a) microglial activation [17-19], (b) astroglial loss and activation [20,21], (c) upregulated ratios of T helper 1 (Th1) cells and proinflammatory cytokines [22-24], and (d) decreased CD4+CD25+FOXP3+ regulatory T (TReg) cell counts [25]. The gene discussed is CD4; the disease is major depressive disorder.