[Eosynophils in parasitic infections--clinical and functional significance].

Eosinophils are multifunctional cells which contain and produce many biologically active substances. Their presence is mainly associated with parasitic infections or allergic manifestations. Eosinophilia is a common feature of helminth infections occurring both in the blood and at local sites of infection. The highly toxic basic proteins in eosinophil granules exert a range of biological effects not only against helminth parasites but also in host tissue being responsible for their damage. Eosinophils have been shown to be strong effectors killing helminth parasites in vitro, especially the larval stages. However, this function in vivo was established only for the very small number of parasites. In the last years an opportunity has appeared to perform experiments with parasites on genetically modified mice: over expressing the gene encoding Il-5 as well as lacking some receptors on eosinophils. These new studies in mice demonstrated that Il-5 and eosinophils had a different impact on different helminth infections. Eosinophilia in human patients has only a limited predictive value for the presence of helminth infections. However, the likelihood of the presence of helminth infections increases considerably with the extent of eosinophilia.