Lack of interference in skin tests by endotoxin in allergen extracts

Endotoxin activity was detected in several commercial allergen extracts. Epicutaneous skin testing using purified lipopolysaccharide (LPS) alone or mixed with allergen extracts demonstrated that LPS had no effect on test results. We conclude that endotoxin present in allergen extracts is unlikely to have any practical implication for epicutaneous skin testing with these extracts.