Abstract: Objective To investigate the effect of tacrolimus on Langerhans cell migration in order to understand the therapeutic mechanism of tacrolimus. Methods C57BL/6 mouse injected with different doses of tacrolimus was stimulated by FITC at ear back. After twelve hours, the number of Langerhans cells which took antigen and migrated to lymph nodes was measured by flow cytometry. The number of Langerhans cells which took antigen and resided in epidermis was examined by immunohistochemical staining. Results After injection with tacrolimus, the number of Langerhans cells which took antigen and migrated to lymph nodes was reduced, especially at 12 hours before stimulation by FITC. The reduction was significantly different between the high dose and low dose injection groups. However,the number of Langerhans cells residing in epidermis was significantly higher in tacrolimus injection group than that in the control. Conclusions Tacrolimus, a new kind of immunosuppressive drug,may probably suppress Langerhans cell migration and therefore inhibit immune response in some diseases.

Key words: Tacrolimus, Langerhans cells, Chemotaxis