Manganese Oxidation State as a Cause of Irritant Patch Test Reactions

摘要

Background: Manganese chloride (MnCI_2) 2.5% is included in the extended metals patch test series to evaluate patients for contact hypersensitivity to this metal salt.Objectives: The objective of this study was to prospectively determine the rate of allergic and irritant patch test reactions to MnCI_2 (Mn(lD), Mn_2O_3 (Mn(lll)), and KMnO_4 (Mn(VlD) in a cohort of patients undergoing patch testing.Methods: Fifty-eight patients were patch tested with MnCI_2, Mn_2O_3, and KMnO_4, each at 2.5% in petrolatum. Patch readings were taken at 48, and 72 or 96 hours, and scored using standard methods. Cultured monolayers of keratinocytes (KCs) were exposed to MnCI_2, Mn_2O_3, and KMnO_4 in aqueous culture medium, and cell survival and cytokine release were studied.Conclusions: MnCI_2 caused irritant patch test reactions in 41% of the cohort, whereas Mn_2O_3 and KMnO_4 caused a significantly lower rate of irritant reactions (both 3%). No allergic morphologies were observed. Similarly, in cultured KC monolayers, only MnCI_2 was cytotoxic to KC and induced tumor necrosis factor a release.The oxidation state of manganese used for patch testing affects the irritancy of this metal salt, as Mn(ll) caused an unacceptably high rate of irritant reactions in a cohort of patients. In vitro studies confirmed these clinical data, as only Mn(ll) was cytotoxic to cultured monolayers of KC.