Mitsuaki Morimoto

Langerhans’ cells in the murine oral mucosa in the inductive phase of delayed type hypersensitivity with 1-chloro-2, 4-dinitrobenzene

We created a murine model of delayed‐type hypersensitivity (DTH) to 1‐chloro‐2, 4‐dinitrobenzene (DNCB). Using this murine model, we compared oral mucosal sensitization and skin sensitization for the difference in reaction during the elicitation phase. Evaluation of sensitizability, using the mouse ear swelling test (MEST) after oral mucosal or skin sensitization, showed that the ear swelling response peaked 24 h after challenge. The optimal induction concentration was 1·0% in both oral mucosal and skin sensitization, resulting in a positive reaction rate of 100%. However, the ear swelling response 24 h after challenge with the optimal concentration of DNCB (1·0%) was significantly lower in oral mucosal than in skin sensitization. We compared the oral mucosal and skin sensitization sites for the number of Langerhans’ cells (LC) and the antigen‐presenting capability in the induction phase. The numbers of F4/80+ major histocompatibility complex (MHC) class II+ LC before induction did not differ significantly between the oral mucosa and the skin. After induction, F4/80+ MHC class II+ LC increased in number, but the increase was significantly smaller in the oral mucosa than in the skin. MEST on anti‐CD86 antibody‐administered mice showed that ear swelling was similarly suppressed after oral mucosal or skin sensitization. In murine models of DTH after oral mucosal sensitization, the number of F4/80+CD86+ LC increased after induction, but the increase was significantly smaller than that in murine models of DTH after skin sensitization. This study showed that, in murine models of DTH, oral mucosal sensitization elicited a weaker reaction than skin sensitization. This was presumably because oral mucosal sensitization induced fewer LC, resulting in lower antigen‐presenting capability.

Objective Assessment of Erythema caused by Metal Patch Testing using an Erythema Index Meter

Abstract The patch test is the most reliable method for diagnosing a metal allergy. However, interpretation of patch test results depends on the experience of the investigator and on the conditions of the individual patient. In the case of patch tests for metal salts, irritant reactions such as pustular or follicular reactions are quite common. Therefore, one must be careful not to interpret irritant reactions as allergic responses, and objective standards to evaluate erythema in patch tests need to be established. In the present study, we attempted to objectively evaluate patch test results for metal salts using an erythema index meter. We used the Erythema Index Difference (EID) (patch test site erythema index (EI) minus the mean EI of healthy skin outside the patch test area and at the unit tape site) rather than the EI itself in order to eliminate the effects of the patch test unit and individual differences. We measured the EID over time in patients with suspected metal allergies to various metals. Significant differences in EID were observed among ++ assessments, + assessments and irritant reactions based on International Contact Dermatitis Research Group (ICDRG) standards. In considering changes in EID over time, allergic and irritant reactions can be discriminated with high sensitivity (73.3%) and specificity (91.2%). These results suggest that the measurement of erythema over time with an erythema index meter is useful for the objective assessment of metal patch test reactions.