An Experimental Model Of Delayed Type Hypersensitivity With HgCl2

Objectives: There have been many reports of disease involving the oral mucosa and skin caused by dental metal allergy. However, the particular mechanism of mercury allergy is not known, and it is often difficult to diagnose and treat. We established a mouse model of delayed-type hypersensitivity (DTH) to HgCl2. We observed the reaction of elicitation phase in oral mucosa sensitization and skin sensitization using this mouse model. Methods: Evaluation of sensitization used the mouse ear swelling test (MEST) after oral mucosa or skin sensitization. It is important to use a challenge dose that causes no measurable irritation at 12, 24, 48 and 72h. Therefore, the highest non-irritation dose was determined from the irritation dose-response results for HgCl2. We topically applied HgCl2 on both sides of the right ear. The ear skin patches contained 20µl of HgCl2 at concentrations of 0.05%, 0.10%, 0.20%, 0.50% or 1.00% (W/V) in a 4:1 (V/V) acetone/olive oil solution (A-O). We sensitized oral mucosa and skin. The back skin patches contained 20µl of HgCl2 at concentrations of 0.20%, 0.50%, 1.00%, 1.50% or 2.00% (W/V) in A-O. For oral mucosa sensitization, we topically applied 20µl of HgCl2 at concentrations of 0.20%, 0.50%, 1.00%, 1.50% or 2.00% (W/V) in A-O, on the both side of dry buccal mucosa. Results: The optimal challenge concentration was 0.50%. The optimal induction concentration was 1.0% in both oral mucosa and skin sensitization, resulting in a positive reaction rate of 100%. Ear swelling due to DTH with HgCl2 was completely suppressed by anti-CD86 antibody or anti-CD80 antibody. Conclusion: These results suggest that HgCl2 can induce DTH via oral mucosa or skin sensitization in mouse.