Mechanism of the interaction mediating killing of Schistosoma mansoni by human eosinophils.

Recent work on the role of eosinophils in immunity to Schistosoma mansoni is summarized. In vitro studies have shown that human eosinophils can kill antibody-covered schistosomula. The killing mediated by eosinophils is associated with adherence of these cells and subsequent degranulation and release of eosinophil major basic protein onto the larvae. The major basic protein itself can kill the larvae. Antibody-dependent eosinophil adherence to the larvae proceeds in at least two distinct steps. The first is mediated by Fc receptors and is relatively weak; the second is a temperature-dependent step which allows a firm irreversible binding of eosinophils to schistosomula. This stable binding is associated with degranulation of eosinophils, a process which appears to contribute to the preferential capacity of this cell to mediate antibody-dependent damage to schistosomula.