Differential adherence of M line Biomphalaria glabrata hemocytes to Schistosoma mansoni and Echinostoma paraensei larvae, and experimental manipulation of hemocyte binding.
The ability of M line strain Biomphalaria glabrata hemocytes to adhere to mother sporocysts (MS) of PR1 Schistosoma mansoni or to MS or daughter rediae (DR) of Echinostoma paraensei was studied using an in vitro hemocyte adherence assay. Hemocytes were significantly more likely to bind to S. mansoni MS than to E. paraensei MS or DR. Hemocyte adherence to E. paraensei MS or DR was significantly increased if glutaraldehyde-fixed larvae were used as targets. Also, E. paraensei MS pretreated with the lectin concanavalin A (Con A) were more likely to be bound by hemocytes than MS pretreated with Con A in the presence of the competing sugar, alpha-methyl mannoside. Pretreatment of hemocytes with Con A increased their ability to bind E. paraensei sporocysts, but the effect was small compared to that achieved by pretreatment of MS with Con A. The lectin probably did not function as a bridging molecule between hemocytes and MS but, rather, altered the MS surface in a way that facilitated adherence. Similarly, adherence to E. paraensei MS was significantly increased if the MS were pretreated with cell-free M line plasma prior to use in adherence assays. Our results indicate that the two parasites provoke fundamentally different responses from M line hemocytes in vitro and that the living tegument can be modified by host humoral factors and by lectins such that hemocyte binding is significantly increased.
Loker
E S
ES
Boston
M E
ME
Bayne
C J
CJ
D000818:Animals; D001700:Biomphalaria / Q000469:parasitology*; D001773:Blood Cells / Q000469:parasitology*; D004449:Echinostoma; D006434:Hemocytes / Q000469:parasitology*; D007814:Larva; D012550:Schistosoma mansoni