Furthermore, elevated numbers and a higher proportion of activated T cells bearing activation markers CD2 + CD25 +, CD3 + CD25 +, HLA-DR + (Maes et al., 1992a), higher blood levels of IL-2R (Liu et al., 2012) and increased number of B cell subsets (Maes et al., 1992c, Robertson et al., 2005) have been detected in patients with major depressive disorder compared with controls. The gene discussed is IL2RA; the disease is major depressive disorder.