Study of the kinetics of in vitro release of known antigens from short ragweed pollen revealed a slow release of AgE (1.5% to 4% release after 16 min) but a rapid release of other highly allergenic components. The rapidly released allergens in 16-min pollen extracts were found to be mainly highly basic proteins including the well-characterized Ra5 molecule along with several hitherto uncharacterized components. Considering previous data that suggest that particles of a similar size to ragweed pollen grains remain in the nose only about 6 to 8 min following inhalation, it is difficult to explain the apparent anomaly between the high biologic potency of 16-min extracts and their low AgE content. Increase in the pH of the extracting buffer from the physiologically normal nasal plH of 5.5 to 6.5 to about pH 8.0 to 8.5 (characteristically found in rhinitis) increased the proportion of AgE released after 16-min extraction by about 10-fold, suggesting that response to allergens in ragweed and other inhalants may enhance AgE release and thereby aggravate allergic symptoms. Detailed comparison of the allergenic activity of AgE and of 16-min and 4-day ragweed extracts in 38 ragweed-sensitive subjects suggested that allergens other than AgE were together more important than AgE in causing ragweed allergy in most patients, although large patient-to-patient differences in relative response were observed. Our data emphasize the need to reevaluate materials used in both diagnosis and treatment of ragweed allergy. The importance of AgE relative to other ragweed pollen components with respect to induction of allergic symptomatology deserves to be placed in a more balanced perspective.