In-vitro antibody-dependent killing of schistosomula of Schistosoma haematobium by human eosinophils.

Schistosomula of S. haematobium have been shown to be susceptible to in vitro killing by eosinophils in the presence of serum from an infected individual. The highest level of killing was found after 48 h in culture. Killing was related to the eosinophil to schistosomula ratio, being highest at 5000: 1. Killing was also related to serum concentration, being highest at a 1/10 final dilution, falling to background levels at a 1/120 final dilution. At a cell: target ratio of 2000: 1 and at a serum dilution of 1/10 eosinophils from subjects with high peripheral blood eosinophil counts were, cell for cell, more active in killing S. haematobium schistosomula than were eosinophils from subjects with lower counts. Sera taken from adults resident in an endemic area gave higher levels of killing in the presence of eosinophils than did sera taken from adults with no history of exposure.