Differences in responses of rat‐ and guinea‐pig‐eosinophils to eosinophil chemotactic factors derived from Angiostrongylus cantonensis

Abstract

Eosinophil chemotactic activity associated with whole worm extracts of the young adult worms (YA) and 1st stage larvae (L1) of Angiostrongylus cantonensis was assessed using guinea-pig- and rat-eosinophils. Both whole worm extracts were potently chemotactic to guinea-pig-eosinophils whereas only the whole worm extract of L1 was chemotactic to rat-eosinophils. Gel filtration chromatography of YA-whole worm extract yielded an eosinophil chemotactic factor (ECF-YA) with an estimated molecular weight of 16,900. ECF-YA was resistant to heating and pronase digestion but sensitive to periodate oxidation, suggesting that chemotactic activity was possibly associated with the sugar portion of the glycoprotein molecule. Guinea-pig- and rat-eosinophils were deactivated by previous incubation with homologous whole worm extracts but not with heterologous ones. When guinea-pig-eosinophils were treated with trypsin or pronase, their chemotaxis to ECF-YA was significantly inhibited, and pronase treatment was more effective. Both deactivated and trypsin-treated guinea-pig-eosinophils completely recovered their chemotaxis responses after in vitro culture for 12 and 24 h, respectively. When those eosinophils were cultured in vitro in the presence of puromycin or cycloheximide, however, their chemotaxis responses could not be recovered. These data clearly indicate that guinea-pig-eosinophils probably possess a kind of receptor (or 'recognition unit') capable of reacting to ECF-YA, and also that the receptor may be protein or glycoprotein molecules, and reproducible.