Cytotoxic reactions of rainbow trout, <i>Salmo gairdneri</i> Richardson, macrophages for larvae of the eye fluke <i>Diplostomum spathaceum</i> (Digenea)

Abstract

The killing ability of rainbrow trout macrophages for the infective larval stages of Diploslomum spathaceum , cercariae and diplostomules, was investigated. Isolated macrophages kill significant numbers of diplostomules at effector: target ratios of 150: 1 or greater. In vitro killing was not increased using antiserum‐coated larvae or in vivo ‐activated macrophages individually, but when they were combined increased killed occurred. Diplostomules were capable of eliciting respiratory burst activity from macrophages in vitro , suggesting that reactive oxygen species may have a role to play in the killing mechanism. The importance of macrophage activation in the protection afforded by immunization against this parasite is discussed.