Allergy to Salsola Kali in a Salsola incanescens-rich area: role of extensive cross allergenicity.

BACKGROUND: Pollens from the Salsola spp. are an important source of respiratory allergy in tropical countries. Our aim was to characterize the IgE binding proteins of S. incanescens pollen extract and study its cross-reactivity with S. kali pollen allergens.
METHODS: Prick tests with S. kali and S. incanescens pollen extracts were performed on eight respiratory allergy patients from Mashhad, Northeast Iran. The antigenic profiles and IgE-binding patterns of S. kali and S. incanescens pollen extracts were compared by SDS-PAGE and Western blotting, using individual sera from the salsola pollen-sensitive patients. Cross-reactivity of proteins in the two weeds was assessed by IgE- immunoblotting inhibition.
RESULTS: S. kali and S. incanescens pollen extracts showed similar IgE-binding profiles in Western blotting. The IgE binding components of 39, 45, 66 and 85 kDa were detected in both pollen extracts. Furthermore, inhibition of the immunoblots revealed extensive inhibition of IgE binding to proteins and a close relationship between these two weeds allergens.
CONCLUSIONS: S. incanescens pollen is a potent allergen source with several IgE binding components that shows a close allergenic relationship with S. kali. Our results suggest that in S. incanescens-rich areas, S. kali pollen extracts could be used as a diagnostic reagent for allergic patients to S. incanescens pollen.