β-Glucans in standardized allergen extracts

Background: Allergen extracts contain variable quantities of bacterial endotoxin. Recent studies have suggested that (1→3)-β-D-glucans (β-glucans), also microbial cell wall components, may have adjuvant properties that could affect allergen immunotherapy. Objective: To determine the quantities of β-glucans in standardized allergen extracts. Materials and Methods : Ninety-four lots of 13 standardized allergen extracts were tested for β-glucan content by Glucatell assay, and for endotoxin content by a specific, chromogenic formulation of the Limulus amebocyte lysate test. Results: Standardized allergen extracts contain variable quantities of endotoxins and β-glucans. As in our previous work, endotoxin activity was greatest in cat pelt and Dermatophagoides farinae, and least in the pollens. There was no correlation between endotoxin and β-glucan levels (r = 0.1887; P = 0.07). β-Glucan content was highest for grass pollen (median content, 10.6 ng/ml; range, 0.4—41.8 ng/ml), ragweed pollen (32.9 ng/ml; range, 6.5—41.2 ng/ml), and cat pelt (25.5 ng/ml; range, 16.7—41.1 ng/ml), and lowest for cat hair (4.9 ng/ml; range, 1.2—10.3 ng/ml), D. farinae (1.2 ng/ml; range, 0.4—5.2 ng/ml) and Dermatophagoides pteronyssinus (1.8 ng/ml; range, 0.4—6.7 ng/ml). Conclusions: β-Glucans are present in standardized allergen extracts. The effects of these quantities of β-glucans on allergen immunotherapy and allergen skin testing require further study.