Helminthotoxic responses of intestinal eosinophils to Trichinella spiralis newborn larvae

Because the gastrointestinal lamina propria is the first line of defense against invasion with Trichinella spiralis newborn larvae, we investigated the helminthotoxic characteristics of isolated lamina propria eosinophils. Eosinophils were isolated from the intestinal lamina propria of rats and purified to nearly 90% purity by a combination of velocity sedimentation through Percoll and unit gravity sedimentation through a continuous gradient of bovine serum albumin. Isolated eosinophils were of high viability and responded to surface receptor stimulation. Freshly isolated intestinal eosinophils lacked cytotoxic capacity when incubated with newborn larvae in the presence of specific antiserum. Peritoneal eosinophils from the same rats exhibited 100% helminthotoxicity after 24 h. Cytotoxicity could be stimulated in the intestinal eosinophils by the addition of recombinant murine interleukin-5.