Lipid transfer protein from Hevea brasiliensis (Hev b 12), a cross-reactive latex protein

BACKGROUND: Latex-allergic individuals experience clinical cross-reactivity to a large number of fruits and vegetables. Much of the cross-reactivity can be attributed to Hev b 6, but evidence indicates that additional cross-reactive allergens may be present. A common pan-allergen, which has not previously been identified in latex, but may contribute to this cross-reactivity is lipid transfer protein (LTP). We sought to determine whether Hevea brasiliensis produces LTP and whether it would bind immunoglobulin E from latex-allergic patients. METHODS: LTP was identified in H. brasiliensis RNA by polymerase chain reaction using degenerate primers. The entire cDNA was obtained by polymerase chain reaction using rapid amplification of cDNA ends reactions. The complete coding sequence for LTP was determined and produced as a recombinant protein using the glutathione S-transferase and pET32 expression systems. Immunoblot analysis of sera from latex-allergic patients was used to determine whether patients recognize LTP as an allergen. RESULTS: We identified a 662-basepair cDNA with a 351-basepair open reading frame that encodes for a 116-amino acid protein. The protein has significant homology to the family of nonspecific LTPs. We expressed the protein as a mature LTP of 92 amino acids with a predicted isoelectric point of 10.8 and molecular weight of 9.3 kDa. Immunoblots demonstrated specific immunoglobulin E for LTP in the sera of 9 of 37 (24%) latex-allergic individuals. CONCLUSIONS: We describe the initial identification of rLTP in H. brasiliensis that may be important as a cross-reactive pan-allergen (Hev b 12)