Regulation of the immune response in lymphatic filariasis and onchocerciasis.

The persistence of microfilariae in the blood or skin accompanied by a prominent eosinophilia and elevated serum IgE levels are common features of human infection with filarial parasites. In this review Christopher King and Thomas Nutman discuss recent findings on the role of interleukin 4 (IL-4), IL-5 and gamma-interferon (IFN-gamma) in the induction of these immediate hypersensitivity responses. They discuss the role of hypersensitivity in immunity, the development of immune tolerance to filarial antigens and suggest that could explain the impaired immune response of some individuals to filarial infections and the persistence of the microfilaremic state.