PubMed · 8369971
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M D Chapman. 1993. Dissecting cockroach allergens.. https://doi.org/10.1111/j.1365-2222.1993.tb03230.x
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We report that a major 23-kDa allergen from German cockroach (Blattella germanica) is a glutathione S-transferase (EC 2.5.1.18; GST). Natural B. germanica GST, purified from cockroach body extracts by glutathione affinity chromatography, and recombinant protein expressed in Escherichia coli using the pET21a vector, showed excellent IgE antibody binding activity. B. germanica GST caused positive immediate skin tests in cockroach-allergic patients using as little as 3 pg of recombinant protein. The NH2-terminal sequence of the natural protein and the deduced amino acid sequence from cDNA were identical except for one substitution (Phe9 --> Cys). Assignment of this protein to the GST superfamily was based on binding to glutathione and sequence identity (42-51%) to the GST-2 subfamily from insects, including Anopheles gambiae and Drosophila melanogaster. B. germanica GST contained 18 of the 26 invariable residues identified in mammalian GST by x-ray crystallography and exhibited enzymic activity against a GST substrate. Our results show that cockroach GST causes IgE antibody responses and is associated with asthma. The data strongly support the view that the immune response to GST plays an important role in allergic diseases.
Ovomucoid, the dominant allergen in hen's egg, is a highly glycosylated protein comprising 186 amino acids arranged in three tandem domains (Gal d 1.1, 1.2, and 1.3). The purpose of this study was to evaluate the allergenic properties of ovomucoid. The three ovomucoid domains were isolated and evaluated with sera from egg allergic patients to determine B cell domain specificity, B cell epitopes, and the relative importance of linear and conformational structures and carbohydrate chains to B cell epitopes. Peripheral blood T cells from egg allergic patients were used to evaluate T-dominant domains and reactivity to reduced and oxidized ovomucoid. There was significantly more IgE activity to the second ovomucoid domain (median percentage of ovomucoid-specific IgE: Gal d 1.2, 40%; Gal d 1.1, 23%; Gal d 1.3, 26%). Quantities of patient IgG Ab were comparable for all three domains. Five IgE and seven IgG binding regions were identified. IgE Ab binding to reduced ovomucoid and IgG binding to oxidized ovomucoid were significantly reduced compared with that to native ovomucoid (28 and 69%, respectively). Peripheral blood T cells of 21 of 33 patients reacted to Gal d 1.3, 18 of 33 reacted to Gal d 1.2, and 18 of 33 reacted to Gal d 1.1. T cell proliferation in vitro in response to reduced and oxidized ovomucoid were significantly greater than that in response to the native protein. These results indicate a dichotomy between T and B cell domain dominance, and the presence of both unique and common IgE and IgG epitopes. Furthermore, the results suggest that conformational B cell epitopes play a more significant role in ovomucoid allergenicity than previously appreciated, and that carbohydrate moieties have a minor effect on allergenicity.
The aim of this study was to investigate the [3H]arachidonic acid metabolism of rat peritoneal macrophages, induced by allergen (ovalbumin) and the impact of interleukin-4 on this process. We established that ovalbumin induces an increase of [3H]arachidonic acid mobilisation from membrane lipids and of [3H]arachidonic acid catabolism, principally by the 5-lipoxygenase pathway, when the macrophages are sensitized and when serum is present. The allergen effect is not modified by the presence of interleukin-4 in the culture medium of macrophages 15 h before the allergen challenge. We also showed that, whereas the basal [3H]arachidonic acid metabolism of macrophages from control and actively sensitized rats is not different, interleukin-4 increases the [3H]arachidonic acid mobilisation and catabolism by cyclooxygenase and 5-lipoxygenase pathways in macrophages from control rats although it does not in macrophages from actively sensitized rats. In macrophages from control rats, the interleukin-4 effect is diminished by the addition of IgEs to their culture medium. In summary, interleukin-4 has an enhancer effect on the macrophage arachidonic acid catabolism that depends on the sensitization condition of the cell but that has no consequences on the further increased arachidonic acid metabolism induced by the allergen.