INDUCTION OF IGE ANTIBODY-RESPONSES BY GLUTATHIONE-S-TRANSFERASE FROMTHE GERMAN-COCKROACH (BLATTELLA-GERMANICA)

We report that a major 23-kDa allergen from German cockroach (Blattell a germanica) is a glutathione S-transferase (EC 2.5.1.18; GST). Natura l B. germanica GST, purified from cockroach body extracts by glutathio ne affinity chromatography, and recombinant protein expressed in Esche richia coli using the pET21a vector, showed excellent IgE antibody bin ding activity. B. germanica GST caused positive immediate skin tests i n cockroach-allergic patients using as little as 3 pg of recombinant p rotein. The NH2-terminal sequence of the natural protein and the deduc ed amino acid sequence from cDNA were identical except for one substit ution (Phe(9) --> Cys). Assignment of this protein to the GST superfam ily was based on binding to glutathione and sequence identity (42-51%) to the GST-S subfamily from insects, including Anopheles gambiae and Drosophila melanogaster. B. germanica GST contained 18 of the 26 invar iable residues identified in mammalian GST by xray crystallography and exhibited enzymic activity against a GST substrate. Our results show that cockroach GST causes IgE antibody responses and is associated wit h asthma. The data strongly support the view that the immune response to GST plays an important role in allergic diseases.