Selective interference with granulocyte function induced by Echinostoma paraensei (Trematoda) larvae in Biomphalaria glabrata (Mollusca).

Various trematode larvae can interfere with the host snail's resistance to the same or unrelated trematode species, chiefly, it appears by interference with the function of the host's granulocytes. In Biomphalaria glabrata infected with the trematodes, Echinostoma paraensei, granulocytes lose their ability to encapsulate the larvae of trematodes to which the hosts were previously resistant. However, the granulocytes in these snails retain their ability to encapsulate injected latex spheres, or larvae of the metastrongyle nematode, Angiostrongylus malaysiensis, and to phagocytose epidermal plates cast off by miracidia of the trematode, Schistosoma mansoni. Cellular infiltration in injured preputial tissue of the snail also was not suppressed by the presence of E. paraensei larvae. Interference with the granulocyte function in B. glabrata induced by E. paraensei infection therefore appears to be a selective phenomenon.