Enhanced helminthotoxic capacity of eosinophils from patients with eosinophilia

To determine whether eosinophils from patients with eosinophilia have an enhanced capacity to kill parasites, we compared purified eosinophils (mean purity, 89 per cent) from 30 patients with various degrees of eosinophilia and with or without infection with Schistosoma mansoni for the capacity to kill schistosomula, the larval stage of S. mansoni, in vitro. There was a significant correlation between peripheral eosinophil count and antibody-dependent, eosinophil-mediated death of parasites after 40 hours of culture (P < 0.0001). Antibody-dependent adherence of eosinophils, measured after two hours of incubation, also correlated with the capacity of the eosinophils to kill the parasites. The correlation between the killing capacity of eosinophils and their peripheral-blood count was observed in patients both with and without S. mansoni infection. We suggest that eosinophilia involves not only a quantitative change in eosinophil numbers but also a qualitative change in functional capacity that renders circulating eosinophils more effective in resisting parasitic infections.