Some factors influencing the production of IgE in the rat

Hall, Elizabeth P (1978) Some factors influencing the production of IgE in the rat. MSc(R) thesis, University of Glasgow.

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In Section I various methods employed for the quantification of IgE are discussed and detailed accounts of two techniques used in this laboratory are presented. Total serum IgE in the rat is estimated using the radioimmunosorbent test (RIST). This 'sandwich' technique employs anti-IgE coupled to paper discs, which binds to IgE present in samples or standards subsequently added. A final incubation with radiolabelled anti-IgE presents the third layer of the 'sandwich', and radioactive counts in each sample are directly proportional to the concentration of IgE present. Antigen specific rat IgE is measured in vivo by the Passive Cutaneous Anaphylaxis (PCA) test. Twenty-four hours after an intradermal injection of the diluted test serum art intravenous challenge of antigen and Evan's blue dye is given. Attachment of antigen to the mast cell-bound IgE results in release of vasoactive compounds with ensuing increased vascular permeability which results in the appearance of a blue area at the injection site. The titre of the serum under test is taken as the reciprocal of the last dilution giving a reaction of 5 mm in diameter. In Section II, experiments are described in which primary and secondary IgE antibody responses were elicited in Hooded Lister rats by intradermal injection or oral administration of very small quantities of egg-albumin. For primary responses the minimum effective dose was found to he 1 mug intradermally and 10 mug orally, both administered with an intraperitoneal injection of B. pertussis adjuvant. In rats immunised with these doses even smaller quantities of antigen evoked booster responses; thus, 1 ng intradermallv and 1 mug orally. Large primary doses (> 100 mug) presented by these routes were, on the other hand, found to be inhibitory to the production of booster IgE responses as was reported previously in intra--peritoneal immunisation experiments. The results are discussed in relation to IgE production and regulation of antigen absorption through mucosal barriers. In Section II, 2, experiments are described which show that the adjuvant used in initial immunisation influences the subsequent occurrence of enhanced responses induced by an antigen challenge (booster response) or helminth infection (potentiated response). Although the level of the primary response was similar following immunisation with egg-albumin (EA) and pertussis (Bp) , aluminium hydroxide (Al(OH)[3]) or complete Freund's adjuvant (CFA) as adjuvant, the booster response was inhibited and the potentiated response enhanced when the latter two adjuvants were used. A significant IgE booster response could only be obtained if SD had been used in initial immunisation. Concavalin A (Con A) could also act as an adjuvant for the induction of an IgE response to EA. Moreover, a subsequent injection of Con A was found to enhance the EA specific response in a manner analogous to an antigen induced booster response. The Con A enhancing effect occurred only in animals primed with EA together with Bp or Con A and not in animals primed with EA in Al(OH)3 or CFA. These results are discussed in relation to the intricacies of IgE production in this model and to more general mechanisms of adjuvant action. In Section II, 3, the ability of different rat strains to produce IgE antibody responses following large and small doses of antigen and infection with N. brasiliensis has been compared. Sprague Dawley rats responded poorly to 1 mg and 1 mug EA, but did produce low level secondary responses. Some degree of inhibition was evident in CFHB and Hooded Lister strains following immunisation with I mg EA, since secondary responses were higher following immunisation with 1 mug of EA. Following antigen challenge, CFY produced similar but low level secondary responses whether they had been initially immunised with a high or low dose of EA, even although a primary response was not detected after immunisation with 1 mug EA. Elevation of total serum IgE was less marked following N. brasiliensis infection in the 'poor' IgE responding strains, and the total serum IgE response was in some cases unaccompanied by potentiation of the EA IgE response. The findings are discussed in relation to the function of regulatory mechanism known to be operative in the control of IgE responses.

Item Type: Thesis (MSc(R))
Qualification Level: Masters
Additional Information: Adviser: Ellen Jarrett
Keywords: Immunology
Date of Award: 1978
Depositing User: Enlighten Team
Unique ID: glathesis:1978-73988
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 23 Sep 2019 15:33
Last Modified: 23 Sep 2019 15:33

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