Trichinella spiralis: in vitro cytotoxicity of peritoneal cells against synchronous newborn larvae of different age.

Two different immune sera obtained from mice infected with muscle larvae (ML) of Trichinella spiralis (oral infection) or injected with 20-h-old newborn larvae (NBL) via retro-orbital venous plexus (intraocular injection) were compared in antibody-dependent cellular cytotoxicity test. Four synchronous stages of NBL, 0-2 h old, 22 24 h old, 46-48 h old and 6 days old (sNBL) were used to study susceptibility of larvae to the cytotoxic reaction of peritoneal cells. Peritoneal cells adhered to and destroyed sNBL of T. spiralis only in the presence of both immune sera. Living sNBL, living sNBL covered by peritoneal cells and dead sNBL were observed in all experimental groups. The lowest percentage of dead sNBL was detected in the 22- to 24-h-old groups. A dramatic increase in mortality was observed in older groups. A greater susceptibility of sNBL to serum obtained from mice infected per os with ML was observed. Serum obtained after oral infection showed higher levels of IgG1 isotype specific to ML than serum obtained after ocular injection.