THE 14.6 KD RUBBER ELONGATION-FACTOR (HEV-B-1) AND 24 KD (HEV-B-3) RUBBER PARTICLE PROTEINS ARE RECOGNIZED BY IGE FROM PATIENTS WITH SPINA-BIFIDA AND LATEX ALLERGY

Two major water-insoluble proteins are located on the surface of rubbe r particles in Hevea brasiliensis latex. A 14.6 kd protein (Hev b 1), found mainly on large rubber particles (>350 nm in diameter), and a 24 kd protein (Hev b 3), found mainly on small rubber particles (average diameter, 70 nm), are recognized by IgE from patients with spina bifi da and latex allergy. Although Hev b 1 (also called the rubber elongat ion factor [REF]) has previously been reported as a major latex allerg en, this conclusion has been disputed on the basis of results from oth er studies. The allergenicity of Hev b 1 is verified in this study by testing the recombinant protein generated from its gene. Because aller genicity is confined to patients with spina bifida and not observed in adults sensitive to latex, it is not a major latex allergen. The iden tification of Hev b 3 as another allergen originating from rubber part icles is confirmed by immunogold labeling and electron microscopy. Obs ervations with the monoclonal antibody USM/RC2 developed against Hev b 3 show that the protein has a tendency to fragment into several polyp eptides of lower molecular weight (from 24 kd to about 5 kd) when stor ed at -20 degrees C. There is also indication of protein aggregation f rom the appearance of proteins with molecular weights greater than 24 kd. Fragmentation of Hev b 3 is induced immediately on he addition of latex B-serum, which is normally compartmentalized in the lutoids in f resh latex. In the preparation of ammoniated latex (used for the manuf acture of latex products), the lutoids ar ruptured, and the released B -serum reacts with Hev b 3 on the rubber particles to give rise to an array of low molecular weight polypeptides that are allergenic to pati ents with spina bifida.