Reactions to the Alcohol-Insoluble Fraction of Ragweed Pollen

Abstract

It was shown by Coca and Grove 1 that tryptic digestion of pollen did not destroy its ability to elicit a positive reaction in allergic individuals, although after dialysis no trace of its original nitrogen-content remained. Stull, Cooke and Chobot 2 found that the active principle of ragweed pollen is present in that fraction which is insoluble in 90-95% alcohol. Black 3 by repeated precipitation of ragweed pollen extract in 60% alcohol and redissolving of the precipitate in acid saline, obtained an extract which contained very little nitrogen, and which gave many of the chemical reactions characteristic of polysaccharides. This fraction also gave typical allergic reactions in 43 ragweed-sensitive patients, and no reactions in 50 normals. The highest dilution giving a reaction when injected intradermally was 1:240,000. Unger, Moore, Cromwell and Seeber, 4 in desensi-tization experiments using both purified protein derivatives and purified polysaccharide fractions, concluded that the specifically active substance in pollen is protein in nature, and that the carbohydrate plays no part in the specificity of their reactions.

To 50 cc. of a 2% aqueous extract of ragweed pollen, 450 cc. of absolute alcohol were added. The resulting precipitate was dissolved in 50 cc. of physiological saline. In control tests, 2% aqueous extracts of pollen were used.

The redissolved precipitate gave typical allergic reactions in individuals sensitive to ragweed pollen. The reaction elicited by the 90% alcohol-insoluble fraction was more intense than that of the 60'% alcohol-insoluble fraction, but the type of reaction was essentially the same in each case.

In the allergic individuals reactions were obtained with the 90% alcohol-insoluble fraction in dilutions of 1:10,000,000, administered intradermally. The intensity of this reaction varied in different individuals from a slight reddening to an intense erythema with the formation of a wheal and pseudopods.