Cytokine profiles in the central nervous system and the spleen during the early course of experimental African trypanosomiasis

Cytokines are important signalling proteins, which have been shown to contr ibute to immunopathogenesis of several inflammatory and infectious diseases such as African trypanosomiasis. The present study was conducted in order to evaluate the early induction of five potential cytokines in the central nervous system (CNS) and spleens from Trypanosoma brucei brucei (T. b. bruc ei)-inoculated and uninfected control Sprague-Dawley rats. In brain, choroi d plexus and spleen, cytokine levels were examined by in situ hybridization and immunohistochemistry, while ELISA was used to measure cytokine levels in cerebrospinal fluid (CSF). Our results showed that interferon (IFN)-gamm a and transforming growth factor (TGF)-beta were highly expressed in all co mpartments, but low interleukin (IL)-4, IL-10 and tumour necrosis factor (T NF)-alpha mRNA levels were registered. The pattern of these cytokines is in context with the severity of the disease because (i) IFN-gamma was previou sly demonstrated to promote parasite growth (ii) TNF-alpha was previously d emonstrated to kill the parasites and (iii) IL-4 was previously demonstrate d to promote antibody production necessary for elimination of the infection . These data support the hypothesis that cytokines may have a role in devel oping the disease either by enhancing the parasite growth or by suppressing the immune response.