FS01.8 Substance‐specific modulation of TNF‐Alpha and IL‐1Beta in human monocytes by para‐Phenylenediamine and not by its autoxidation product Bandrowski’s Base

Abstract

Para‐phenylenediamine (PPD), an arylamine dye, is a strong allergen causing allergic contact dermatitis. Cytokines such as TNF‐α and IL‐1beta are key mediators in the initiation of this reaction. Both cytokines are predominantly produced by stimulated monocytes and macroghages. We investigated the responses of PPD and Bandrowski's base (BB), an autoxidation product of PPD in human monocytes. We isolated monocytes from healthy volunteers and incubated them with the allergens. TNF‐α and IL‐1beta mRNA expression and protein levels were estimated after 45 min, 2 h, 4 h and 24 h after allergen contact. IL‐1beta and TNF‐alpha were measured in cell culture supernatants by ELISA (n = 7) and mRNA expression was determined by real‐time RT‐PCR. We found that PPD reduced TNF‐α protein secretion by 20–69.9%(n = 6). Further, IL‐1beta levels were decreased by 44–98%. The same tendency was found studying IL‐1beta and TNF‐α mRNA steady state levels (n = 3; 1 h incubation). These effects were substance‐specific and not found for PPD derivatives nor for the autoxidation product BB. These findings suggest that PPD may specifically modify immune responses by directly infering with the cellular proinflammatory cytokine network.This study was supported by the EU.