The stability of short ragweed pollen extract as measured by skin test and antigen E

A short ragweed pollen extract stored at 4 degrees C was shown to retain its skin reactivity for 18 mo, although 60% of the antigen E was lost. When stored at higher temperatures, the extracts had a markedly reduced skin reactivity for some individuals, but retained full reactivity in others even though the antigen E was markedly diminished. Thus, some ragweed-sensitive individuals are very sensitive to antigen E, which is heat-labile, but some have a major sensitivity to other allergens, which are heat-stable. During the 18-mo course of this study, skin test reactions to a similar extract did not show significant variability.