IMMUNOLOGICAL RESPONSE OF RAT TO INFECTION WITH TAENIA-TAENIAEFORMIS .6. ROLE OF IMMEDIATE HYPERSENSITIVITY IN RESISTANCE TO RE-INFECTION

  • 1 January 1978
    • journal article
    • research article
    • Vol. 34  (3) , 565-570
Abstract
Chemical inhibitors of immediate hypersensitivity were used to treat rats passively immunized against T. taeniaeformis with serum containing 7S.gamma.2.alpha. and reaginic antibodies. There was no significant reduction in protection against oral challenge with eggs in these animals, indicating that reagin-mediated hypersensitivity reactions were not an essential component of the protective mechanism. Systemic reagin sensitization results in an acceleration of the rate at which challenge organisms were destroyed in immune rats. By 12 h after infection most of the parasites were killed in the livers of rats which were passively immunized and reagin-sensitized; a large proportion survived in rats passively immunized, but not reagin-sensitized. This effect of reagin appeared to be limited to the early stages of resistance since parallel groups left for 21 days after challenge were equally well protected. In an effort to determine if vasoactive amines liberated by reagin-mediated reactions could act directly on invading parasites, early larval stages of T. taeniaeformis were exposed to histamine or serotonin (5HT) in vitro or in vivo. Consistent results were not obtained, but significant inhibition (P < 0.05) of viability of parasites exposed to histamine occurred on 2 occasions. Significant (P < 0.01) inhibition of infectivity of T. taeniaeformis also resulted when peritoneal anaphylactic diffusate was introduced into isolated gut loops containing hatched embryos of the parasite. The possible means whereby reagins may participate in protective immunity to infectious organisms was discussed.