[Immunologic mechanisms influencing the host-parasite relations in snail-trematode systems]

This is a review article based on about 100 papers from leading world newspapers. The main features and the way of action of the snail's immune system are described. The mechanisms of discrimination between self and non-self are presented in detail, including characterization of interacting components of host (cellular and humoral factors) and parasite (a sporocyst surface) origin. The phenomena of molecular disguise and molecular mimicry are discussed in the context of the compatibility between a host and a parasite. The possible ways of killing parasite are indicated, with special regard to production of reactive oxygen intermediates by hemocytes during the process of killing.