The role of eosinophils in parasitic helminth infections: Insights from genetically modified mice

Eosinophilia-an increase in the number of eosinophils in the blood or tissu es-has historically been recognized as a distinctive feature of helminth in fections in mammals. Yet the precise functions of these cells are still poo rly understood. Many scientists consider that their primary function is pro tection against parasites, although there is little unequivocal in vivo evi dence to prove this. Eosinophils are also responsible for considerable path ology in mammals because they are inevitably present in large numbers in in flammatory lesions associated with helminth infections or allergic conditio ns. In this review, Carolyn Behm and Karen Ovington outline some of the cel lular and biological properties of eosinophils and evaluate the evidence fo r their role(s) in parasitic infections.