Characterization of glutathione S-transferase from dust mite, Der p 8 and its immunoglobulin E cross-reactivity with cockroach glutathione S-transferase.

BACKGROUND: Sensitization to mite and cockroach allergens is common, and diagnosis and therapy of allergy can be further complicated by the presence of allergen isoforms and panallergens. Purified recombinant and native allergens are useful for studies to resolve such problems. OBJECTIVE: To assess the allergenicity of native and recombinant mite glutathione S-transferase (GST) (Der p 8) and study the IgE cross-reactivity between Der p 8 and cockroach GST. METHODS: Der p 8 cDNA encoding a new isoform was isolated and expressed in yeast. Native Der p 8 was affinity purified from mite extract. IgE reactivity to native and recombinant Der p 8 was assessed by ELISA using sera from allergic subjects from Taiwan, Singapore and Malaysia. IgE cross-reactivity between Der p 8 and cockroach GST was examined by IgE inhibition assays. RESULTS: Our Der p 8 cDNA encoded a basic isoform (pI=8.5) containing six polymorphic residues located at positions 46, 106, 149, 160, 167 and 184. At least 8 isoforms of native Der p 8 were detected by two-dimensionalgel and immunoblot analyses. Sera from Taiwanese asthmatics showed 96% and 84% IgE reactivity to native Der p 8 and recombinant Der p 8, respectively. Native Der p 8 showed 75% and 65% IgE reactivity with sera from Malaysia and Singapore, respectively. CONCLUSIONS: A high frequency of sensitization to mite GST among allergic subjects was observed but the titres of IgE reactivity were low. The IgE cross-reactivity between mite and cockroach GST suggests that GST is a panallergen.

Detection of antibodies in cats infected with filarial parasites by the indirect immunofluorescence technique.

The indirect immunofluorescence technique in cats infected with filarial parasites, Brugia malayi, B. pahangi and D. repens were studied. The antibody level in infected microfilaraemic cats was higher than that in infected amicrofilaraemic cats and uninfected cats. Papain-treated whole microfilariae appeared to be more sensitive than the sonicated antigen. The comparative IFA titres using papain-treated and sonicated microfilarial antigen, in the serodiagnosis of filariasis is presented.

Brugia malayi and B. pahangi: cultivation in vitro of infective larvae to the fourth and fifth stages.

Cultivation of fourth stage Brugia pahangi and B. malayi larvae from infective larvae (stage 3) were obtained in culture medium RPMI 1640 supplemented with 10% human AB serum and an LCC-MK2 rhesus monkey kidney continuous cell line feeder layer. This culture system kept larvae alive in excess of 7 weeks, and served as a source for collection of the worms' secretory, excretory, and moulting antigens.