THE MAIN IGE-BINDING EPITOPE OF A MAJOR LATEX ALLERGEN, PROHEVEIN, ISPRESENT IN ITS N-TERMINAL 43-AMINO ACID FRAGMENT, HEVEIN

Polypeptides of natural rubber latex (NRL) that elute from surgeon's g loves and other manufactured rubber products can sensitize exposed ind ividuals and elicit severe hypersensitivity reactions, Previously, we showed that prohevein is a major allergen in NRL, the source material for rubber manufacturing. To analyze which region of the molecule carr ies the main IgE-binding epitope(s), we purified prohevein and its C-d omain from NRL by gel filtration, reverse phase chromatography, and el ectroelution. In immunoblotting, prohevein bound IgE from 15 of 20 (75 %), and the prohevein C-domain from 3 of 20 (15%) latex-allergic patie nt sera. In ELISA, 36 of 52 (69%) patient sera showed IgE binding to p rohevein, whereas 11 of 52 (21%) sera had IgE to prohevein C-domain. W e then purified from a brand of highly allergenic surgeon's gloves six hydrophilic peptides that revealed in amino-terminal sequencing 100% identity to the N-terminus of prohevein, In mass spectrometry, all pur ified peptides gave a molecular mass of 4719 +/- 1.9 daltons, which co rresponds to the molecular mass of hevein (4719.1 daltons), a 43-amino acid N-terminal fragment of prohevein. Purified hevein inhibited 72% of IgE binding from pooled sera of NRL-allergic patients to solid phas e glove extract and 45% of IgE binding to solid phase NRL. Of the 43 N RL-allergic patient sera tested, 56% showed IgE Abs to purified hevein in ELISA. In skin prick testing, purified hevein elicited positive re actions in three-quarters of the latex-allergic patients tested. These results indicate that the majority of prohevein's IgE-binding ability resides in its N-terminal fragment, known as hevein. In one highly al lergenic latex glove examined, the majority of IgE-binding ability was attributable to hevein molecules, suggesting that these peptides can be significant sensitizers in NRL allergy.