Synergistic immunosuppression by candida in HIV infection: a cytokine based analysis

Candida is a common opportunistic pathogen in HIV infection and is regarded a signal infection for progression to AIDS. Cytokine imbalances between Th1/Th2 groups have been described in both candida and HIV infections. A study was undertaken to assess the role of candida in furthering immunosuppression in HIV infection based on cytokine levels and CD4 cell counts. 30 Indian subjects were enrolled; 10 HIV positive patients with and 10 without mucosal candidiasis and 10 age matched controls. Th1 cytokines; interleukin (IL) 2, IL 12 and interferon (IFN) gamma, Th2 cytokines; IL 4, IL 6, IL 10 and tumor necrosis factor (TNF) alpha with CD 4 cell counts were estimated using ELISA in all subjects. CD4 cell counts were reduced in both patient groups as compared to controls; significantly more in patients with both HIV and candida infections. There was a decrease in Th1 cytokine levels in all patients; lower levels of Th1 cytokines were seen in patients with both infections. Among the Th2 cytokines, there was a significant increase in the levels of IL 6, IL 10 and TNF alpha in both patient groups; IL 10 and TNF alpha values were significantly raised in patients with dual HIV and candida infections as compared to the other patients. There was no difference in IL 4 values across the subject groups. A positive correlation between CD4 cell counts and Th1 cytokine levels and a negative correlation with Th2 cytokines were noted; these were stronger in patients with both HIV and candidiasis. Thus, there was a Th1/Th2 cytokine imbalance with CD4 cell count reduction in all HIV infected patients, which was more pronounced in patients with both infections. It can be concluded that, owing to the depressed CD4 cell count and Th1 response and increased Th2 cytokines in patients with both candidiasis and HIV as compared to patients with only HIV candidiasis may have a synergistic immunosuppressive effect with HIV in patients with dual infections.