Immunology Review Corner

By Thao N. Tran, M.D., Stony Brook University Hospital- SUNY; Karla Lowe, M.D., Walter Reed Medical Center; and Todd Levin, M.D., Medical College of Georgia

Questions

Chapter 35 - Preparation and Standardization of Allergen Extracts

1. Approximately what percentage of seasonal allergic rhinitis patients has positive skin tests to weed pollens?
a. 5-15%
b. 20-35%
c. 40-50%
d. 60-75%

2. Which of the following is considered the most efficient collection method for pollen source materials?
a. Vacuum collection
b. Rotorod sampler
c. Water setting
d. Drying, grinding, and sieving flower heads

3. Which of the following statements is true about fungal allergen extracts?
a. Since fungal source materials are produced from well-defined seed culture collections and fungi have minimal genetic variability between strains, it is safe to assume identically labeled fungal allergen products from different manufacturers are quantitively and qualitively similar.
b. In the United States, no fungal allergen extracts have been standardized.
c. Alternaria alternata is the first of the 200 standardized fungal allergen extracts to be approved by the FDA.
d. Fungal allergen extracts are produced from fungal source materials that contain either spores-only or mycelia-only.

4. The difference between standardized cat hair and cat pelt extracts is:
a. They contain different concentrations of the major allergen, Fel d 1.
b. They contain equivalent concentrations of Fel d 1, but cat pelt extracts have 10- to 100-fold higher concentration of cat albumin.
c. The methods of measuring potency of Fel d 1 are different: radial immunodiffusion assay for cat hair extracts, and isoelectric focusing for cat pelt extracts.
d. Allergen concentrations in cat hair extracts are designated in PNU/mL and cat pelt extracts are designated in equivalent BAU/mL.

5. For stinging insects, which anatomical site is the most common source of insect allergen extract?
a. Venom sac
b. Whole body
c. Cast skins
d. Salivary glands

6. Which of the following statements is true regarding food allergens?
a. Cooking rarely changes the allergenicity of foods.
b. The American Academy of Pediatrics recommends allowing fish consumption at 18 months of age.
c. Allergen content is more stable over time in foods versus pollen.
d. Milk, eggs, peanut, wheat, soy, fish, shellfish and tree nuts cause 90% of reactions.

7. Which of the following statements is true regarding allergen extracts?
a. Standardized allergens are labeled by weight of source material extracted per volume of extracting fluid (w/v).
b. Maximum recovery of allergen depends mostly on addition of glycerin to the extract.
c. Protein yields are increased with slightly alkaline conditions.
d. For a particular allergen made by different manufacturers, biologic activity correlates directly with w/v.

8. Which of the following is available only as a nonstandardized allergen extract in the United States?
a. White-faced hornet (Vespa spp.)
b. Orchard grass (Dactylis glomerata)
c. American cockroach (Periplaneta Americana)
d. Cat hair (Felis domesticus)

9. Stability of allergen extracts depends on:
a. Composition: animal dander extracts have very high protease levels and should only be mixed with cockroach or fungal extracts
b. Dilution: allergens may get absorbed by the surfaces of the glass and syringe, and lose their potency
c. Formulation: aqueous formulations are more resistant to deterioration by high temperature than the glycerinated formulations
d. Storage: it is recommended to store extracts at 20 to 25 degrees Celsius

10. For nonstandardized extracts in final containers with 50% or more glycerin stored at 2-8 degrees Celsius, when should you no longer use the product for immunotherapy?
a. 12 months
b. 18 months
c. 24 months
d. 36 months

11. In allergen standardization, which method is used to assess initial overall allergenicity?
a. Parallel-line bioassay
b. Inhibition radioimmunoassay
c. Intradermal dilution for 50 mm sum of erythema determines the bioequivalent allergy units
d. Isoelectric focusing

ANSWERS
1. d, page 573
2. a, page 573
3. b, pages 574-575
4. b, pages 575, 580-581
5. a, page 576
6. d, page 576
7. c, pages 576, 579
8. c, page 577
9. b, pages 578-579
10. d, page 579
11. c, page 581