Abstract
Allergens from somatic extracts of adult Nippostrongylus brasilinesis worms were
characterized 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 N. brasiliensis.
Monoclonal mouse anti rat-IgE was used a a specific probe. The major 14,000 -
17,000 MW allergens, partially purified by electrolution, retained activity by
passive cutaneous anaphylaxis (PCA). Other immunoblobulin isotypes, notably IgG
also bound to allergens on Western blot. The specificites 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 N. brasiliensis. 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 fo 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 IgG2a> The light chains wee apparently resistant to digestion. ..The presence of IgE-befring 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 N.
brasiliensis. 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.
