Studies on the allergens of ragweed pollen: A review

Abstract

The results reported by numerous investigators who have attempted over the last forty years to isolate and establish the composition of the allergen(s) in the pollens of short and giant ragweed are conflicting. None of the investigations reviewed has provided a satisfactory proof that the allergen(s) have been separated in a pure form. It would seem that the following two studies represent the most advanced stages in the characterization of allergens in ragweed pollens: The work of Goldfarb and associates 58 has led to the isolation from giant ragweed pollen, of a fraction (Trifidin A) which was shown to be chemically, electrophoretically, and immunologically a single entity. On standing in the cold in distilled water, however, it was degraded into at least three components: a ninhydrin-stainable material, arabinose, and another reducing substance. We 117 have recently isolated, by use of paper electrophoresis, a highly allergenically active fraction from short ragweed pollen (AA 1-D), which was shown to contain a pigment and peptide(s) composed of eight amino acids: arginine, lysine, glutamic acid, glycine, alanine, hydroxyproline, valine, and norleucine. The pigment could be removed from this fraction without loss of allergenic activity. On the other hand, hydrolysis of the peptide(s) resulted in a complete loss of allergenic activity; therefore, it was concluded that the peptide(s) appeared to be the allergen(s) in short ragweed pollen. Furthermore, it was shown that 10 −7 mg. of fraction AA 1-D was allergenically as potent as 10 −4 mg. of the whole water-soluble extract of ragweed pollen. In view of the extremely high biologic potency of fraction AA 1-D, and in view of the fact that allergenically active fractions isolated in previous studies all contained some nitrogen material, it may be suggested that the allergenicity of ragweed pollen is due to peptide(s), which may be complexed with other carriers, such as proteins, carbohydrates, or pigments.