PROHEVEIN FROM THE RUBBER TREE (HEVEA-BRASILIENSIS) IS A MAJOR LATEX ALLERGEN

Background There is general agreement that proteins eluting from diffe rent natural rubber latex products can cause immediate type hypersensi tivity reactions in latex-allergic patients. However, there is as yet no consensus as to what are the most important allergens in natural ru bber latex. Objective We wanted to purify and characterize at the prim ary structure level three natural latex proteins, suggested to represe nt significant allergens. Methods Proteins were purified from ultracen trifuged bottom fraction of natural rubber latex using high performanc e liquid chromatography gel filtration and reversed phase chromatograp hy. Purified proteins were subjected to tryptic cleavage, peptide sepa ration and amino acid sequencing. Immunoblotting was used to demonstra te IgE antibodies to the purified proteins in sera from latex-allergic patients. Results A 20 kDa protein was identified by amino acid seque ncing as prohevein, a major protein in the rubber tree Hevea brasilien sis, and a 30 kDa natural rubber latex protein as hevamine, another es sential rubber tree protein. A third, previously undescribed natural r ubber latex protein, showed high homology to several plant endo-1,3-be ta-glucosidases. In immunoblotting, the purified prohevein bound IgE a ntibodies from 24/29 (83%) sera of latex-allergic patients including p ositive results in 4/6 latex-allergic children with spina bifida or ot her congenital anomalies. The purified prohevein elicited positive ski n-prick test reactions in all six latex-allergic patients showing IgE to prohevein. The purified 36 kDa protein bound IgE from 6/29 (21%) la tex-allergic sera, and the purified hevamine from only 1/29 patient se ra. Conclusion The observed high frequency of IgE antibodies to prohev ein suggests that this protein is a major natural rubber latex allerge n