Anti-IFN-γ autoantibodies and disseminated opportunistic infections in immunocompetent Indian adults.

OBJECTIVES

Though anti-IFN-γ autoantibodies are associated with adult-onset immunodeficiency among Asians, they are not routinely tested. Despite rising reports of disseminated opportunistic infections in apparently immunocompetent individuals, the clinical course and prevalence of anti-IFN-γ autoantibodies remain poorly characterized. We evaluated the association between severe opportunistic infections and plasma anti-IFN-γ antibodies and IL-12 levels.

METHODS

This cross-sectional study evaluated levels of anti-IFN-γ autoantibodies and IL-12 in HIV negative, apparently immunocompetent patients with disseminated intracellular opportunistic infections (Group 1; n = 44) or persistent tuberculosis (Group 2; n = 41) against healthy controls (Group 3; n = 34).

RESULTS

Common infections in Group 1 were disseminated non-tuberculous mycobacterial infections (40.9%), cryptococcosis (36.4%), and disseminated histoplasmosis (13.6%). Median anti-IFN-γ autoantibody concentrations were significantly higher in Group 1 [66.02 ng/mL; IQR 52.19-85.86; p = 0.004] and Group 2 [65.46 ng/mL; IQR 52.31-86.03; p = 0.004] than in Group 3 [44.77 ng/mL; IQR 28.56-69.93]. When compared to controls, IL-12 levels were significantly elevated in Group 1 (p = 0.006). In Group 1, three patients had relapses (6.8%), and three patients died (6.8%).

CONCLUSIONS

Patients with disseminated intracellular opportunistic infections and those with persistent tuberculosis had significantly higher levels of anti- IFN-γ autoantibodies than healthy controls. IL-12 levels were significantly higher in patients with disseminated intracellular opportunistic infections than among healthy controls. There was no significant difference in IL-12 levels among patients with persistent tuberculosis and healthy controls.