CD4 and infection: Previous studies have suggested that patients have high serum anti-IFN-γ autoantibody titers, which can inhibit IFN-γ-induced CD4+ T cell STAT-1 phosphorylation and IL-12 production, leading to serious dysfunction in the T helper 1 cell response [15, 16], which is the cause of multiple severe, and sometimes fatal, intracellular pathogen infections in HIV-negative patients.