Dr. Murai Éva szerk.: Parasitologia Hungarica 22. (Budapest, 1989)

Effector mechanisms of the protective immunity induced by intestinal helminths* Review article Dr. Tibor KASSAI Department of Parasitology and Zoology, University of Veterinary Science, Budapest, Hungary "Effector mechanisms of the protective immunity induced by intestinal helminths" - Kassai, T. - Parasit, hung. 22: 5-20. 1989. ABSTRACT. A selective review is given of current research on the mechanisms involved in immunological expulsion of intestinal helminths. A wide area of research is to characterize the specific cellular components and their respective function in bringing about host protection. The information accrued in recent years in analytic studies on kinetics and activation of various types of inflammatory and immune operational cells, on the mediator substances (amines, prostaglandins, proteases, leukotrienes, interleukins, interferon, etc.) released by these cells, on specific antibodies raised by helminth infections is reviewed. It Is pointed out that so far correlative rather than direct causal relationship has been demonstrated between mucosal cells or cell products and worm expulsion. Mucus trapping of intestinal worms has been suggested to be in a cause-andeffect relationship between mucus secretion and worm rejection. Most worms, however, are rejected from immune hosts without any apparent involvement of mucus trapping. The interplay between parasite antigens, mucosal mast cells, and a variety of specific and non-specific factors of mucosal secretions results in inflammatory changes of the mucosa bringing about worm expulsion. Intestinal nematodes are not killed when rejected from immune hosts, their metabolism is only reversibly depressed. The metabolic restraints, and fall in ATP level developing rapidly in worms in near anoxic conditions resulting in decreased motility and altered locomotion capacity present an example of the mechanism which may affect worms to cope with the changes of their mucosal microenvironment. Despite the abundant research and great deal of information available on various facets of the protective immunity against intestinal helminths, no important conceptual development took place since the early 80ths. The need for a reinforced analysis of the interaction of host immunity and worm physiology is stressed. Invited paper presented at the Fifth European Multicolloquium of Parasitology, 4-9 September, 1988, Budapest, Hungary.