Severe Malaria-The Role Of Regulatory Cytokines

 ABSTRACT An anti-inflammatory cytokine, interleukin 10 (IL-10) suppresses T-helper 1 cells (Th1) route and enhances the Th2 route in mice by boosting the antibody response. The present work studied the effect of exogenous IL-10 in the system of BALB/C mice during the development severe anaemia. BALB/C mice developed severe anaemia within 2-3 weeks after inoculation with 106 parasitised RBCs (pRBCs) intraperitoneally. BALB/C mice treated with recombinant IL-10 developed patent parasitaemia of 7% on day 7-post inoculation as compared to 10.5% in controls. Nevertheless, there was no significant difference between the two groups haematologically (parasitaemia P>0.01, haemoglobin levels P>0.01, reticulocytosis P>0.01 and in hematocrit values P> 0.01). There was generally a positive correlation between anaemia and the parasite count and reticulocytosis, but negative correlation with haemoglobin levels and the hematocrit levels measured. Cytokine levels in vivo and in vitro were determined using the ELISA technique. The endogenous IL-10 measured was higher in the IL-10 treated than the controls. However there was no difference statistically between the mortality of the two groups, though it appeared to be slower in the IL-10 treated BALB/C mice. Also, there was no significant difference between the TNF-a measured in both sera and the spleen cell culture supernatants of the two groups. IgG and IgM were measured by means of Immunofluorescence Antibody Test (IFAT) and using whole / blood stages of the parasites as antigens. The role of immunoglobulin in erythrophagocytosis was observed because there was enhanced erythrophagocytosis between the 7th and 12th day, that was when lgG2a recorded the highest peak value in both test and control mice. On the other hand, lgG3 recorded low levels with a significant increase in TN F-a during the same period. The use of mitogen in vitro showed that activation of T cells results in the production of cytokines.