Prohevein from the rubber tree (Hevea brasiliensis) is a major latex allergen.

BACKGROUND: There is general agreement that proteins eluting from different natural rubber latex products can cause immediate type hypersensitivity reactions in latex-allergic patients. However, there is as yet no consensus as to what are the most important allergens in natural rubber latex. OBJECTIVE: We wanted to purify and characterize at the primary structure level three natural latex proteins, suggested to represent significant allergens. METHODS: Proteins were purified from ultracentrifuged bottom fraction of natural rubber latex using high performance liquid chromatography gel filtration and reversed phase chromatography. Purified proteins were subjected to tryptic cleavage, peptide separation and amino acid sequencing. Immunoblotting was used to demonstrate IgE antibodies to the purified proteins in sera from latex-allergic patients. RESULTS: A 20 kDa protein was identified by amino acid sequencing as prohevein, a major protein in the rubber tree Hevea brasiliensis, and a 30 kDa natural rubber latex protein as hevamine, another essential rubber tree protein. A third, previously undescribed natural rubber latex protein, showed high homology to several plant endo-1,3-beta-glucosidases. In immunoblotting, the purified prohevein bound IgE antibodies from 24/29 (83%) sera of latex-allergic patients including positive results in 4/6 latex-allergic children with spina bifida or other congenital anomalies. The purified prohevein elicited positive skin-prick test reactions in all six latex-allergic patients showing IgE to prohevein. The purified 36 kDa protein bound IgE from 6/29 (21%) latex-allergic sera, and the purified hevamine from only 1/29 patient sera. CONCLUSION: The observed high frequency of IgE antibodies to prohevein suggests that this protein is a major natural rubber latex allergen.

Frequent occurrence of IgE and IgG4 antibodies against saliva of Aedes communis and Aedes aegypti mosquitoes in children.

We examined the prevalence of IgE and IgG4 class antibodies to the saliva of Aedes communis and Aedes aegypti mosquitoes in the sera of three groups of exposed children using a sensitive immunoblot method. The frequencies of IgE antibodies to the major 36-kD A. communis and A. aegypti saliva antigens ranged from 82 to 90% in the 20 Finnish, 17 Kenyan, and 20 Mexican children. The corresponding IgG4 antibody frequencies were 85, 41, and 20%, respectively. The nonexposed 20 Icelandic children did not show IgE or IgG4 antisaliva antibodies. Several of the Finnish children showed also IgE and IgG4 antibodies to a 22-kD A. communis saliva antigen. The Finnish children abnormally sensitive to mosquito bites had frequently IgE and IgG4 antibodies to the 22-kD A. communis saliva antigen, suggesting that these antibodies play a role in the pathogenesis of immediate cutaneous mosquito bite reactions. In contrast to this, no increase was found in the A. aegypti antibody frequencies in the Kenyan and Mexican children with papular urticaria, suggesting that humoral immune response to A. aegypti saliva is not involved in the development of this disorder. The present results show that humoral IgE and IgG4 immune responses to Aedes mosquito saliva antigens is common in children living both in temperature and tropical zones. The IgE antibodies seem to be involved in the immediate mosquito bite whealing, and the occurrence of the IgG4 subclass antisaliva antibodies might be an indicator of intense mosquito bite exposure.