Further studies on the allergenic activity of protein and nonprotein nitrogen fractions of ragweed pollen extract

Abstract

1. 1. Protein prepared either by dialysis of ragweed extract, ammonium sulfate precipitation, or precipitation by alcohol and ether at −10° C., neutralized the skin sensitizing antibody of ragweed sensitive serum at approximately the same strength as whole extract when all were diluted to contain the same amount of protein nitrogen. This is further evidence that the activity of ragweed pollen in producing allergic reactions is associated with protein. 2. 2. The dialyzable nitrogen of ragweed pollen extract is shown to be inactive in neutralization of the skin sensitizing antibody. A small amount of this fraction is precipitated by phosphotungstic acid. 3. 3. Dried protein precipitated from ragweed extract at −10° C. with alcohol and ether when redissolved after ten months showed almost the same activity in neutralization as fresh extract. 4. 4. Ragweed extract at the end of ten months showed a loss of protein, and the remaining protein showed a marked loss of neutralizing capacity.