Studies in severe combined immunodeficiency mice reconstituted with human peripheral blood mononuclear cells (PBMC) suggested that Vγ9/Vδ2 T cell may mediate rapid clearance of intraperitoneal infections, by enhancing monocyte-mediated killing of bacteria through production of interferon (IFN)-γ and tumor necrosis factor (TNF)-α [26]. Here, TNF is linked to severe combined immunodeficiency.