EVALUATION OF THE ATOPY PATCH TEST AND THE CUTANEOUS LATE-PHASE REACTION AS RELEVANT MODELS FOR THE STUDY OF ALLERGIC INFLAMMATION IN PATIENTS WITH ATOPIC ECZEMA

Objective: The study was designed to evaluate the atopy patch test (AP T) and the late-phase reaction (LPR) after intracutaneous allergen inj ection as models for the study of allergic inflammation in atopic ecze ma. Methods: Immunocytochemistry was used to analyze skin biopsy speci mens from sites of APTs and LPRs at 2 and 24 hours and To compare thes e with lesional and nonlesional skin of patients with atopic eczema. R esults: A lack of neutrophil infiltration in specimens from both the A PT and lesional skin sites was observed, whereas neutrophils were abun dantly present in the specimens from LPR sites. With double-staining t echniques it was demonstrated that the few neutrophils present in spec imens from APT sites and in lesional skin were mostly located in intra vascular areas, whereas in the LPR specimens they were located predomi nantly in extravascular areas. Eosinophils infiltrated at an earlier t ime point in the LPR as compared with the APT. Furthermore, there was a decrease of intact mast cells in the LPR sites compared with the APT sites and lesional skin. No significant difference in T-cell number w as observed between the two tests. Upregulation of E-selectin expressi on on endothelial cells occurred at an earlier time point in the LPR a s compared with the APT. Conclusion: There are important differences i n cellular infiltrate between the APT and the LPR. The close macroscop ic and microscopic similarities between the specimens from APT sites a nd lesional skin of patients with atopic eczema support the argument t hat the APT is a more valid in vivo model with which to study allergic inflammation in atopic eczema than the LPR.