Characterisation of the IgE response in Nippostrongylus brasiliensis infected rats

• Main Author: McGuigan, Andrew Colin
• Published: University of Edinburgh 1992
• Subjects: 591.9857
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.666232

Allergens from somatic extracts of adult <i>Nippostrongylus brasilinesis</i> worms were characteriszed by SDS-PAGE and Western blotting. Seven allergens, with molecular weight ranging from 14,000 - 69,000 were identified after blotting with hyperimmune serum (HIS) from rat immunized by several infections with <i>N. brasiliensis</i>. Monoclonal mouse anti rat - IgE was used as a specific probe. The major 14,000-17,000 MW allergens, partially purified by electrolution, retained activity by passive cutaneous anaphylaxis (PCA). Other immunoglobulin isotypes, notably IgC<SUB>1</SUB> also bound to allergens on Western blot. The specificities of other immunoglobulin isotypes and IgE were compared by sequential incubation of blotted allergens with IgE - depleted HIS and with affinity-purified serum IgE. Despite retaining biological activity by PCA, the affinity-purified IgE proved to be insufficiently specific for use on Western blots. The range of allergens detected and the kinetics of appearance of parasite-specific IgE differed between LOU. Hooded Lister, August and F334 undergoing primary infection with <i>N. brasiliensis</i>. Whereas August rats responded uniformly, there were variations in the timing and specificity of IgE responses between individual rats within the other strains. Nevertheless, it was possible to classify LOU and Wister rats as early and F334 rats as late responders. Internalization of IgE within the cytoplasm of intestinal mucosal mast cells (MMC) of rodents infected with intestinal nematodes, and the absence of this isotype from the cytoplasm of connective tissue mast cells (CTMC) suggested that the MMC granule protease, rat mast cell protease II (RMCP II), might fail to catabolize IgE. However, when compared with the granule protease RMCP I from CTMC. RMCP II was more efficient in catabolizing the heavy chains of both IgE and IGG<SUB>2a</SUB>. The light chains were apparently resistant to digestion. The presence of IgE-bearing cell populations in bone marrow, peripheral blood, and peritoneal cavity, was monitored by flow cytometry in normal Wister rats and during the course of infection with <i>N. brasiliensis</i>. The proportions of IgE-bearing cells in the peritoneum and bone marrow increased on day 10 and, in peripheral blood on day 15. The IgE-bearing cells in each compartment were of mixed phenotype.