The self-cure reaction in Nippostrongylus brasiliensis infections in the rat

Douthwaite, Rosalind Mary (1967) The self-cure reaction in Nippostrongylus brasiliensis infections in the rat. MSc(R) thesis, University of Glasgow.

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This work was undertaken in an attempt to determine the mechanism of the "self-cure reaction" in Nippostronaylus brasiliensis infections in the laboratory rat. In this reaction the immune mechanisms of the rat cause the rapid expulsion of the adult worms from the email intestine at the end of the second week of a primary larval infection. As a starting point it was necessary to obtain mare quantitative information on the kinetics of self-cure, In terms of worm burdens, sew ratios and faecal egg counts, than had previously boon described in the literature. Following a primary infection it was sheen that egg output by the parasites reached a maximum en the 10th day; thereafter it dropped rapidly to around sore by the 15th day. By the 12th day the expulsion of the parasites had begun and by the 16th day only about 1% of the original worm burden remained. In order to facilitate the study of the it effect of anti body on the parasites a surgical technique was developed in which serum and adult worms were transferred to a previously uninfected rat. Using this technique it was shown that both immune and hyperimmune serum interfered significantly with either the establishment or the longevity of a transplanted adult population. In an attempt to assess if humoral antibody has any direct effect on the adult parasites, the oxygen consumption of worms in hyperimmune scram was compared with that of worms in normal serum, It appeared that the former consumed loss oxygen over a 20-hour period than the latter. The significance of this observation was discussed. If antibody does have a direct effect on the parasites in some way debilitating them so as to make them prone to expulsion it is necessary to demonstrate how it comes into contact with the worms. By the use of 51Cr labelled red cells it was sheen that the ingestion of blood by the parasites could h ruled out as a means of bringing significant quantities of antibody into contact with the worms. Alternatively it was considered possible that antibody may reach the worms as a result of a worm-induced hypersensitive reaction in the intestinal mucosa. The capillary permeability associated with much a reaction night allow appreciable quantities of antibody into the intestinal lumen where it could act directly on the parasites. In support of this theory are the findings of the experiments reported in Sections II and III, which were designed to find if anaphylaxis did occur and was an essential part of the self-cure reaction. These results were as follows: 1) As early as 7 days after an initial infection rats could he shocked by the intravenous injection of N. brasiliensis antigen. 2) This reaction was principally expressed in gross alterations in the small intestine which resembled those present at self-cure. 3) Susceptibility to intestinal anaphylaxis could be passively transferred to normal rats by a prior injection of hypermmune serum. 4) The antihistaminic promethazine hydrochloride interfered significantly with the expulsion of the adult population at self-cure. 5) Cortisone completely blocked the self-cure of a primary infection and abolished the anaphylactic reaction induced by the intravenous injection of N. brasiliensis antigen. 6) There was a sigaificantly increased output of urinary free histamine in male rats during the period of self-cure as compared with the output on the proceeding days. 7) There were indications that the concentration of histamine in heavily infected areas of the intestinal mucosa of infected rats increased after self-cure. These results are discussed in relation to recent publications by other workers in this field. It was concluded that intestinal ansphylaris is probably an essential part of the self-cure reaction and that its role may be to facilitate the passage of antibody into the lumen of the small intestine.

Item Type: Thesis (MSc(R))
Qualification Level: Masters
Additional Information: Advisers: D R Newth; G M Urquhart
Keywords: Veterinary science, Parasitology, Immunology
Date of Award: 1967
Depositing User: Enlighten Team
Unique ID: glathesis:1967-72678
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 11 Jun 2019 11:06
Last Modified: 11 Jun 2019 11:06

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