IMMUNOREGULATION IN HUMAN LYMPHATIC FILARIASIS - THE ROLE OF INTERLEUKIN-10

In humans with lymphatic filariasis microfilaremia is associated with a parasite antigen-specific hyporesponsiveness when assessed by cell p roliferation and secretion of interleukin-2 and interferon-gamma. Hypo responsiveness in these individuals is not only parasite antigen-speci fic but appears to be limited to Th1-type responses. Th2 mediated resp onses such as IL-5 secretion and IgE antibody production to parasite a ntigens are generally strong and usually no different than those seen in immunologically more reactive amicrofilaremic individuals with chro nic lymphatic pathology. The mechanisms by which Th1 responses are inh ibited have not yet been elucidated, but some studies suggest that dow n-regulatory cytokines such as IL-10 may be involved in this process. Mononuclear cells from microfilaremic individuals have been found to s ecrete greater quantities of IL-10 spontaneously and in response to pa rasite antigens. In this review, mechanisms by which IL-10 may be indu ced by the parasite and the mode by which IL-10 may regulate parasite antigen-specific Th1 responses in these individuals are discussed.