Purification and partial characterization of a 67-kD cross-reactive allergen from Imperata cylindrica pollen extract

Background: Grass pollens are known To induce type I allergic reactions in a large number of genetically predisposed individuals. Earlier studies have recognized Imperata cylindrica (Ic) pollen as an important source of aeroa llergen which contained 7 IgE binding proteins in the MW range of 85-16 kD. Objectives: To isolate, purify and characterize a cross-reactive allergeni c protein from Ic pollen extract for diagnosis and therapy of grass pollen allergy. Methodology: Ic pollen extract was fractionated using DEAE Sephade x A-50, Sephadex G-200 and Mono Q column. Allergenic activity of the fracti ons was checked by ELISA, skin tests, ELISA inhibition and immunoblot using sera of Ic-sensitive patients. A 67-kD protein was purified to homogeneity from Ic-VIII, The allergenic determinants of this protein were identified by SDS-PAGE and immunoblot after CNBr treatment. Result-sr Among Ic fractio ns, Ic-VIII was highly potent by ELISA, skin tests and showed cross-reactiv ity with 4 other tropical grasses by immunoblot and ELISA inhibition. The s ubfraction Ic-VIIIe1 of Ic-VIII showed a band at 67 kD on SDS-PAGE, On CNBr treatment, it gave 7 peptides, 3 of which were found to be allergenic. Con clusion: A 67-kD protein (Ic-VIIIe1) was isolated, purified to homogeneity and partially characterized. It showed cross-reactivity with tropical grass es tested and contained at least three allergenic determinants. Copyright ( C) 2000 S. Karger AG, Basel.