Related Experiment Video
Updated: May 26, 2026

Quantification of the Immunosuppressant Tacrolimus on Dried Blood Spots Using LC-MS/MS
Published on: November 8, 2015
The effects of FK506 on refractory inflammatory myopathies
Takao Mitsui1, Yukiko Kuroda, Shu-Ichi Ueno
1Department of Neurology, Tokushima National Hospital, National Hospital Organization, Kamojima, Yoshinogawa, Tokushima, Japan. tmitsui@tokusima.hosp.go.jp
Abstract:
We performed an observational clinical study, the effects of tacrolimus (FK506) on the thymic output in patients with refractory inflammatory myopathies. Sixteen patients with polymyositis (PM) and 15 with dermatomyositis (DM) were treated orally with tacrolimus. Serum CK levels significantly decreased 2 to 4 months after tacrolimus therapy (p < 0.01), and MRC (Medical Research Council) scores were significantly improved 2 months after tacrolimus therapy (p < 0.01). T-cell receptor excision circle (TREC) content, a proxy for thymic export was not significantly different from that in age-matched controls, except for an increase in the TREC content within CD8+ single positive cells in patients with DM. TREC contents within double-positive cells and CD4+ single-positive cells were significantly decreased 4 M after tacrolimus therapy (p < 0.05) in PM/DM patients. Tacrolimus treatment significantly attenuated TREC content within cultured CD4+CD8- cells from PM/DMpatients (p < 0.05), but total cell counts were not significantly changed. These results indicate that tacrolimus therapy suppresses not only activated T-lymphocytes, but also some naïve T-cell subsets in both PM and DM.
Related Concept Videos
Drugs for Treatment of Crohn's Disease in IBD Using Immunomodulatory Agents
Drugs for Treatment of Crohn's Disease in IBD Using Biologic Agents: Anti-TNF
Inhibitors of Viral Protein Synthesis
NF-κB-dependent Signaling Pathway
NF-κB-dependent Signaling Mechanism
The heterodimer of NF-κB...