Immunotherapy: Open Access
Open Access

Abstract

Evaluation of Changes in Skin Reactivity by Skin Prick Test Titration

Sten Dreborg, Margareta Holgersson and Christian Moller

Background: Parallel line bioassay (PLBA) has been acknowledged being the gold standard for estimation of changes in skin reactivity during (immuno-)therapy.

Objective: To study changes in skin prick test (SPT) estimated by skin prick test titration, wheal area and sum of wheal areas in relation to PLBA.

Methods: Data from a published immunotherapy trial using skin titration with half 10 log steps were evaluated using endpoint titration, wheal areas, histamine equivalent allergen concentration using PLBA as gold standard.

Results: Endpoint titration and PLBA correlated (r=0.76) and the slope of the correlation, b (0.8) was not significantly different from 1, i.e. expressed the same result, were interchangeable. Furthermore, the result was expressed in change in allergen concentration, Ca. The area of all wheals and the area of the wheal induced by the highest concentration also correlated, but to a lesser degree (b=0.36 and 0.41, respectively), to PLBA significantly different from 1, i.e. did not express the same result.

Conclusions: Estimation of the SPT during therapy expressed as change in endpoint concentration correlated to changes by PLBA. However, earlier described simple methods, expressing the change in skin sensitivity as change in histamine equivalent concentration, should be preferred.