Background and design: Past observations have shown increased irritancy in patients with "conditioned hyperirritability" due to active dermatitis, including atopic dermatitis (AD). In less active atopic conditions, irritancy levels are less certain. We have utilized 48-hour Finn Chamber testing with graded dilutions of sodium lauryl sulfate to detect irritancy thresholds in well-defined groups of patients with AD, inactive AD, and allergic respiratory disease with no dermatitis and in normal nonatopic subjects.
Results: Significantly greater frequency of response to sodium lauryl sulfate in both AD groups and also in patients with allergic rhinitis with no dermatitis was seen. Effective concentrations of sodium lauryl sulfate causing irritation in 50% or more of subjects (ED50) ranged from 0.0625% to 0.31% in all atopic groups, percentages that were significantly lower than the normal ED50 of 0.60%. Response intensity was also significantly greater in each atopic group.
Conclusions: Our results showed significantly greater irritant responses in atopic subjects with no skin disease or in subjects with inactive AD and confirmed past findings that showed greatly increased irritancy in patients with active AD. We hypothesize that abnormal intrinsic hyperreactivity in inflammatory cells, rather than in skin cells, in atopic individuals predisposes to a lowered threshold of irritant responsiveness.