This study aimed to determine the clinical efficacy and effects of tacrolimus in treating myasthenia gravis (MG).

A total of 45 outpatients and inpatients were divided into a tacrolimus group (n=15) and non-tacrolimus group (n=30): those in the former group were treated with 3mg/day of tacrolimus for 24 weeks, while those in the latter (control) group took other immunosuppressants (prednisone, azathioprine combined with prednisone). Each group was evaluated at weeks 4, 8, 12, 16, 20 and 24 by Myasthenia Gravis Foundation of America Quantitative Myasthenia Gravis (MGFA-QMG) Test, activities of daily living (ADL) profiles, and manual muscle (MMT) and fatigue tests. Dynamic changes in CD4⁺CD25^+high cells were tested by flow cytometry. Inflammatory cytokines were also evaluated in the tacrolimus group.

Efficacy index scores decreased significantly compared with baseline at every test week in both groups (P<0.01), although improvements were more evident with than without tacrolimus treatment (F=9.312, P<0.01 vs. F=24.551, P<0.01 and F=10.710, P<0.01). At week 24, peripheral blood CD4⁺CD25^+high T cells with tacrolimus decreased significantly (P<0.01), but increased significantly without tacrolimus (P<0.01). During treatment, CD19⁺BAFF-R B cells in peripheral blood decreased in both groups (P<0.05). Interferon (IFN)-γ concentrations in peripheral blood also diminished significantly with tacrolimus (P<0.01).

A relatively low dose of tacrolimus can affect multiple immune-system targets and, thus, can treat MG effectively in terms of both clinical symptoms and immunological responses.