Scientific Publications by FDA Staff

Clin Exp Allergy 2007 Jul;37(7):1033-9

Biological potency of German cockroach allergen extracts determined in an inner city population.

Slater JE, James R, Pongracic JA, Liu AH, Sarpong S, Sampson HA, Satinover SM, Woodfolk JA, Mitchell HE, Gergen PJ, Eggleston PA

Slater JE (reprint author), US FDA, Ctr Biol Evaluat & Res, 1401 Rockville Pike, Rockville, MD 20852 USA US FDA, Ctr Biol Evaluat & Res, Rockville, MD 20852 USA Rho Inc, Chapel Hill, NC USA Childrens Mem Hosp, Chicago, IL 60614 USA Natl Jewish Med & Res Ctr, Denver, CO USA Howard Univ, Washington, DC 20059 USA Mt Sinai Sch Med, New York, NY USA Univ Virginia, Hlth Syst, Charlottesville, VA 22903 USA NIAID, NIH, Bethesda, MD 20892 USA Johns Hopkins Univ, Sch Med, Baltimore, MD 21218 USA

Background Cockroach allergy is an important cause of inner city asthma. To perform valid studies on the diagnosis and treatment of cockroach allergy, biological potencies of test extracts need to be established, and a surrogate in vitro test for biological potency should be chosen. Methods Sixty-two cockroach-allergic adult subjects were recruited for quantitative skin testing with three commercial German cockroach extracts. The intradermal D50 values were determined using linear interpolation, and the biologic potencies were determined from D50 data. The extracts were also analysed for relative potency, using a competition ELISA, and for specific allergen content, using a two-site ELISA. Results Estimates of each extract's D50 were analysable in 48-55 subjects, with D50s between 10.3 and 11.8. All three extracts were bioequivalent using pre-set criteria. The biological potencies of the extracts were 1738-8570 bioequivalent allergy units (BAU)/mL (geometric mean=3300), and these relative potencies were similar to those estimated by competition ELISA and specific allergen content. IgE against cockroach allergens were detected in sera from 34 subjects with analysable D50s, and 17 subjects had IgE directed against specific cockroach allergens. Although the presence of anti-Bla g 5 correlated with the subjects' skin test responses for 2/3 extracts, no single allergen was immunodominant. Antibody responses among the subjects were heterogeneous. Conclusions Although commercial cockroach extracts are relatively low in potency, immunotherapeutic doses should be achievable. Biological potency may be estimated using D50 testing, a combination of specific allergen determinations, or by an overall potency assay such as the competition ELISA. Capsule Summary The biological potency of three German cockroach allergen extracts, determined in an inner city population, was 1738-8570 BAU/mL. No one allergen was immunodominant, and surrogate in vitro testing methods were examined.