Isolation of a purified allergen from Kentucky blue grass pollen

An allergenic fraction, designated as C-I-2-6, was isolated from among the allergenic constituents present in the dialysate of the aqueous extract of defatted Kentucky blue grass (KBG) pollen by a combination of gel filtration, ion-exchange chromatography and preparative isoelectrofocusing. This fraction was shown in consist of glycoprotein with a molecular size corresponding to 10,000 daltons and of two compounds with closely related pI values (4.5--4.9); its protein moiety contained all the amino acids except cysteine. As demonstrated by crossed immunoelectrophoresis with a sheep anti-R serum, fraction C-I-2-6 shared the antigenic determinants of 2 of the 15 antigenic components of the nondialysable components, i.e. retentate (R) of the aqueous extract of KBG pollen. Remarkably, in spite of the markedly lower molecular weight than R, fraction C-I-2-6 possessed all the allergenic determinants of R responsible for inducing murine IgE antibodies.