Regulatory effects of Th1‐type (IFN‐γ, IL‐12) and Th2‐type cytokines (IL‐10, IL‐13) on parasite‐specific cellular responsiveness in Onchocerca volvulus‐infected humans and exposed endemic controls

The present study investigated in vitro the regulatory effects of T helper 1 (Th1)‐type (interferon‐γ, IFN‐γ; interleukin‐12, IL‐12) and Th2‐type cytokines (IL‐10, IL‐13) on Onchocerca volvulus‐specific cellular reactivity in onchocerciasis patients, and in exposed endemic control individuals presenting no clinical and parasitological signs of disease. In both patients and controls, addition of IL‐10 dose‐dependently depressed O. volvulus antigen (OvAg)‐specific cellular proliferation, and peripheral blood mononuclear cells (PBMC) from patients who were more sensitive to the suppressive effect of IL‐10 than those from endemic controls. However, neutralization of IL‐10 by specific antibody did not reverse cellular hyporesponsiveness. In contrast to the inhibitory effects of IL‐10, exogenous IL‐12 and IL‐13 augmented PBMC proliferative responses to OvAg both in patients and controls (P