Discriminative ability and function of the immunobiological recognition system of the snail helix pomatia

Renwrantz, L.; Schaencke, W.; Harm, H.; Erl, H.; Liebsch, H.; Gercken, J.

Journal of Comparative Physiology B Biochemical Systemic and Environmental Physiology 141(4): 477-488


ISSN/ISBN: 0174-1578
Accession: 005168749

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The internal defense mechanism of H. pomatia discriminates between different types of foreign cells as demonstrated by determinations of their clearance rates. The rate of elimination is not dependent on the size of foreign cells but on their molecular surface properties. Circulating hemocytes are not involved in the 1st phase of the clearance event, which is characterized by an accumulation of nonself cells in the digestive gland, kidney and foot muscle of Helix. Light microscopic studies of these organs reveal nonself cells to be attached to the membrane of cells lining hemolymph sinuses. The attachment of certain types of foreign cells is apparently mediated by opsonins as their clearance depends on the opsonin level of the hemolymph, whereas others are cleared without involvement of opsonizing molecules. Membrane bound molecules of the latter type of nonself cells seem to directly interact with carbohydrate-specific combining sites on the membranes of cells of the sinus walls, as their binding can be inhibited by N-acetyl-galactosamine, and N-acetyl-glucosamine. The 2nd phase of clearance apparently involves the attraction of circulating hemocytes by organ-trapped foreign cells. The number of hemocytes in circulation decreases significantly, whereafter a rising percentage of hemocytes containing foreign cells can be observed in the circulation.