Circulating cytokines in pulmonary tuberculosis according to HIV status and dietary iron content.

Abstract

OBJECTIVE: To evaluate human immunodeficiency virus (HIV) serology, dietary iron and serum concentrations of markers of T-helper type (Th) 1 and Th-2 immune pathways in the setting of tuberculosis (TB). METHODS: A total of 49 patients with pulmonary TB in rural Zimbabwe, 32 of whom were HIV-positive, were evaluated at presentation and over 10 weeks of anti-tuberculosis treatment. RESULTS: Interleukin (IL) 12 and neopterin, Th-1 markers, were both elevated at presentation in 92% of the subjects. In contrast, only 23% had elevation of the Th-2 marker, IL-4. Neopterin and IL-6 concentrations decreased over 10 weeks of treatment (P <or= 0.005), but IL-12 and NO(2)/NO(3) increased (P <or= 0.012). IL-12 and neopterin concentrations were higher in HIV-positive subjects compared to HIV-negative subjects (P < 0.0001), while IL-4 concentrations were lower (P = 0.001). Patients were classified as having high vs. normal dietary iron based on the consumption of iron-rich traditional beer. IL-12 and NO(2)/NO(3) concentrations were lower with high dietary iron (P <or= 0.002). HIV-positive individuals with high dietary iron had lower neopterin concentrations compared to HIV-positive individuals with low dietary iron (P < 0.0001). CONCLUSION: Increased iron in pulmonary TB may lead to attenuation of the Th-1 immune response, especially with HIV seropositivity. Iron status may be an important but under-evaluated risk factor in the course of TB and HIV infection.