Purification and partial characterization ofa 67-kD cross-react ive 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 aeroallergen which contained 7 IgE binding proteins in the MW range of 85-16 kD.


OBJECTIVE
To isolate, purify and characterize a cross-reactive allergenic protein from Ic pollen extract for diagnosis and therapy of grass pollen allergy.


METHODS
Ic pollen extract was fractionated using DEAE Sephadex A-50, Sephadex G-200 and Mono Q column. Allergenic activity of the fractions 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.


RESULTS
Among Ic fractions, Ic-VIII was highly potent by ELISA, skin tests and showed cross-reactivity with 4 other tropical grasses by immunoblot and ELISA inhibition. The subfraction 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.


CONCLUSIONS
A 67-kD protein (Ic-VIIIe1) was isolated, purified to homogeneity and partially characterized. It showed cross-reactivity with tropical grasses tested and contained at least three allergenic determinants.
Verma
J
J
Centre for Biochemical Technology, Delhi, India.
Singh
B P
BP
Gangal
S V
SV
Arora
N
N
Sridhara
S
S
D000485:Allergens / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification*; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000175:diagnosis / Q000209:etiology; D015151:Immunoblotting; D010936:Plant Extracts / Q000737:chemistry / Q000276:immunology; D006109:Poaceae / Q000276:immunology*; D011058:Pollen / Q000737:chemistry / Q000276:immunology*; D012882:Skin Tests
D000485:Allergens; D010936:Plant Extracts