In vivo and in vitro characterization of Allpyral grass pollen extracts.

The Food and Drug Administration, Center for Biologics Evaluation and Research (CBER) has developed methodology to standardize both aqueous and freeze-dried (lyophilized) extracts. Thus far, it has not been determined whether or not this methodology can be used to standardize alum-adsorbed extracts. This study was designed to examine the in vivo and in vitro potency of selected Allpyral grass pollen extracts, including timothy, orchard grass, perennial ryegrass, sweet vernalgrass, and meadow fescue. Puncture testing was performed on highly grass-sensitive subjects with the concentrate of each of the five Allpyral grass extracts. Additionally, puncture testing was done on 22 subjects to compare Allpyral timothy grass with a lyophilized, standardized timothy grass extract. The ID50EAL (Intradermal Dilution for 50 mm sum of Erythema determines the Allergy Unit) skin test method was used to determine allergy units of the Allpyral extracts. Relative potency of the Allpyral timothy extracts to a timothy laboratory standard was determined using an ELISA-inhibition assay. Intradermal tests were also performed to examine the potency of the supernatant obtained after centrifugation of the whole Allpyral timothy extract. The puncture test responses to the Allpyral timothy extracts were less than those to the lyophilized extract. Those 10,000 PNU/mL Allpyral grass pollen extracts tested were determined to contain a calculated 10,000 BAU/mL. By ELISA inhibition, the Allpyral timothy extracts were determined to be approximately 1,000-fold less potent than the laboratory standard. The estimated concentration of the supernatant preparation to elicit a target response was notably (mean = 1,175 times) greater than that of the whole Allpyral timothy extract needed to elicit the same erythema response.(ABSTRACT TRUNCATED AT 250 WORDS)