Expression of Adhesion Molecules in Early Allergic Patch Test Reactions

In order to study the relevance of intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1) and endothelial leukocyte adhesion molecule 1 (ELAM-1) for lymphocyte extravasation in the early phase of allergic contact dermatitis, the time courses of lymphocyte infiltration and adhesion molecule expression during initiation of this disorder were determined. Sequential biopsies of positive allergic patch test reactions were obtained 4, 8, 16 and 24 h after antigen application, cryostat sectioned and stained with monoclonal antibodies for ICAM-1, VCAM-1, ELAM-1 and lymphocytes by use of an immunoperoxidase technique. The slides were evaluated semiquantitatively according to appropriate gradation scales that had been defined separately for the staining with each antibody. Our results show that there is a significant upregulation of VCAM-1 and ELAM-1 expression within the first 8 h after antigen application, when lymphocyte extravasation is just beginning. In contrast, ICAM-1 is already expressed in higher levels in normal skin and is hardly enhanced during the first 8 h of patch test reactions. The main influx of lymphocytes occurs 16-24 h after antigen application and is accompanied by a further increase in all three adhesion molecules. We conclude that VCAM-1 and ELAM-1 rather than ICAM-1 may be of particular importance for the start phase of allergic contact dermatitis and that all three of them contribute to an amplification of this inflammation.