Comparison of cytokine plasma levels in human African trypanosomiasis

Background: Immunological studies suggest that human African trypanosomiasis (HAT) is associated with inflammatory responses. A better understanding of the complex cytokine interactions regulating HAT infections is essential to elucidate the mechanisms of generalized immunosuppression. Method: We determined levels of interleukin (IL)-2, IL-4, IL-6, IL-10, tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma protein levels in plasma samples from three groups of individuals from the Democratic Republic of Congo: (i) HAT cases; (ii) seropositive individuals for whom parasite detection was negative and (ii) controls. Results: Plasma levels of six cytokines were significantly higher in HAT cases than in both controls (P < 0.003) and seropositive individuals (P < 0.016). IL-2 and IL-10 concentrations were significantly lower (P < 0.02) in the seropositive group than in the control one. Conclusion: Human African trypanosomiasis leads to the development of strong cytokine responses, indicating the potential involvement of IL-2 and IL-10 in the phenomenon of seropositivity without parasitological confirmation. This strongly suggests the involvement of immunity in this particular aspect of HAT epidemiology.