Studies of allergen and allergoid preparations from purified timothy (Phleum pratense) pollen extracts. I. Physicochemical characteristics and binding to allergen-specific human IgE.

Physicochemical and in vitro allergenic properties of two different preparations of timothy (Phleum pratense) pollen were compared. The refined allergen extract, timothy B, contained proteins of molecular weights from 10,000 to 45,000 daltons. The allergoid preparation, which was prepared by mild treatment of the partially purified extract with formaldehyde, possessed only a trace of activity in the RAST inhibition assay. The formaldehyde treatment also resulted in a shift of the net charge of proteins to the more acidic site, as demonstrated by isoelectric focusing. Furthermore, it was shown that the activities of naturally occurring enzymes of native allergen extracts were reduced considerably. Only traces of acid phosphatase activity could be demonstrated in timothy B allergoid.