Isolation of a low molecular weight constituent from Kentucky blue grass pollen possessing carrier activity of high molecular weight constituent(s).

An immunologically active fraction, designated as C-I-3 was isolated from the dialysate of the aqueous extract of defatted Kentucky Blue Grass pollen by differential dialysis and gel filtration. This fraction was shown to consist of a glycoprotein with a molecular size corresponding to 4,800 daltons and with a pI value of 3.6, and to contain all amino acids except cysteine. The intraperitoneal administration of C-I-3 in saline into mice or rats prior to their immunization with the nondialyzable constituents of the aqueous extract of Kentucky Blue Grass (i.e., the retentate, R) in presence of Al(OH)3 resulted in the enhanced production of anti-R IgE antibodies. The enhancement of the anti-R murine IgE response was shown in adoptive cell transfer experiments to be due to the generation of R-specific T helper cells. Hence, it is suggested that the structural elucidation of C-I-3 may prove useful in establishing the nature of carrier determinant(s) of the major allergenic components of Kentucky Blue Grass pollen.