Schistosoma mansoni: interleukin-1 increases phagocytosis and superoxide production by hemocytes and decreases output of cercariae in schistosome-susceptible Biomphalaria glabrata.
Decreases in the number of Schistosoma mansoni cercariae released from susceptible M-line Biomphalaria glabrata were detected following injection with the recombinant human cytokine, interleukin-1. No differences in either the time post-exposure at which shedding began or the percentage of snails shedding cercariae were detected between interleukin-1 injected, heat-inactivated interleukin-1 injected, or sham injected controls. However, sham injected and heat-inactivated interleukin-1 injected snails maintained significantly higher (approximately three-fold) levels of cercarial production compared to interleukin-1 injected snails over 8 weeks of cercarial shedding. Injection of interleukin-1 into schistosome-susceptible (M-line) and resistant (13-16-R1) strains of B. glabrata increased hemocyte phagocytosis of target particles and phagocytosis stimulated O2- production in both snail strains at 24 hr postexposure to the parasite. Resistant 13-16-R1 snails maintained, on average, 2.4 times the number of O2- producing phagocytic cells than did M-line susceptible snails, indicating that the incomplete abrogation of cercarial shedding in M-line snails may be due to an inadequate number of activated circulating effector cells in these snails. These data strongly support the contention that the evolutionarily conserved cytokine, interleukin-1, or a molecule in snail plasma with interleukin-1-like immunospecificity, biological activity, and function plays a significant role in the maintenance of susceptibility or resistance to S. mansoni infection in B. glabrata. Finally, these data also supply evidence for the evolutionary conservation of the function and role of interleukin-1, O2-, and antioxidant defense mechanisms in this host-parasite relationship.
Connors
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VA
Division of Biological Sciences, University of Montana, Missoula 59812.
de Buron
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Granath
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WO
D000818:Animals; D001700:Biomphalaria / Q000276:immunology / Q000469:parasitology*; D004199:Disease Vectors; D006434:Hemocytes / Q000276:immunology*; D007375:Interleukin-1 / Q000276:immunology*; D010587:Phagocytosis; D011994:Recombinant Proteins / Q000276:immunology; D012550:Schistosoma mansoni / Q000276:immunology*; D013481:Superoxides / Q000378:metabolism
D007375:Interleukin-1; D011994:Recombinant Proteins; D013481:Superoxides