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 det ermined whether or not this methodology can be used to standardize alu m-adsorbed extracts. This study was designed to examine the in vivo an d in vitro potency of selected Allpyral grass pollen extracts, includi ng timothy, orchard grass, perennial ryegrass, sweet vernalgrass, and meadow fescue. Puncture testing was performed on highly grass-sensitiv e subjects with the concentrate of each of the five Allpyral grass ext racts. Additionally, puncture testing was done on 22 subjects to compa re Allpyral timothy grass with a lyophilized, standardized timothy gra ss extract. The ID(50)EAL (Intradermal Dilution for 50 mm sum of Eryth ema determines the Allergy Unit) skin test method was used to determin e allergy units of the Allpyral extracts. Relative potency of the Allp yral 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 centrifugati on of the whole Allpyral timothy extract. The puncture test responses to the Allpyral timothy extracts were less than those to the lyophiliz ed extract. Those 10,000 PNU/mL Allpyral grass pollen extracts tested were determined to contain a calculated 10,000 BAU/mL. By ELISA inhibi tion, the Allpyral timothy extracts were determined to be approximatel y 1,000-fold less potent than the laboratory standard The estimated co ncentration of the supernatant preparation to elicit a target response was notably (mean = 1,175 times) greater than that of the whole Allpy ral timothy extract needed to elicit the same erythema response. These studies suggest that a modification of the Food and Drug Administrati on, CBER procedure used to standardize lyophilized and aqueous extract s may also be used to standardize Allpyral grass pollen extracts and t hat most of the biologic activity in Allpyral grass extracts is presen t in the suspended material.