Recombinant human interleukin-1-mediated killing of Schistosoma mansoni primary sporocysts in Biomphalaria glabrata.
Previous work has indicated that injection of recombinant-human interleukin (rhIL)-1beta in Schistosoma mansoni-infected M-line Biomphalaria glabrata resulted in a significant reduction in the number of cercariae shed. The purpose of the present work was to determine if primary sporocysts were killed following rhIL-1beta injection in susceptible snails and, if so, to determine if killing was the direct result of hemocyte activity. Counting of primary sporocysts indicated a 50% reduction in the number surviving at 3 days PE in snails from 2 susceptible strains following injection. Histological analysis indicated that killing occurred with little-to-no observable hemocyte/parasite contact, whereas short-term culture of primary sporocysts with cell-free plasma (hemolymph) from injected snails rapidly initiated killing in vitro. Because levels of a snail IL-1-like molecule (SnaIL-1) drop significantly following schistosome exposure in M-line snails, because resistant snails maintain higher SnaIL-1 levels following infection, and because rhIL-1beta upregulates hemocyte cytotoxic mechanisms, these data support the contention that SnaIL-1 plays a role in determining resistance in B. glabrata. These data also indicate that schistosome death may be separated from parasite encapsulation by hemocytes and that an as yet unidentified humoral killing mechanism/factor may exist in B. glabrata. Lastly, these data further support the hypothesis that cytokine-like molecules are important, functionally conserved immunodefense mediators in both vertebrates and invertebrates.
Connors
V A
VA
Natural Sciences and Engineering-Biology, University of South Carolina-Spartanburg, 29303, USA.
de Buron
I
I
Jourdane
J
J
Théron
A
A
Agner
A
A
Granath
W O
WO
D000704:Analysis of Variance; D000818:Animals; D001700:Biomphalaria / Q000469:parasitology*; D004199:Disease Vectors; D006801:Humans; D007375:Interleukin-1 / Q000276:immunology / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000276:immunology / Q000494:pharmacology; D012550:Schistosoma mansoni / Q000187:drug effects* / Q000276:immunology
D007375:Interleukin-1; D011994:Recombinant Proteins