ab22208

Rapid inhibitory effect of Tacrolimus on T cell migration by suppressing CD29-related functions

Y. Munakata, T. Saito, T. Watanabe, H. Fujii, C. Morimoto

Division of Rheumatology and Hematology, Tohoku University Graduate School of Medicine, Sendai, Japan and the Department of Clinical Immunology and AIDS Research Center, Institute of Medical Science, University of Tokyo, Tokyo, Japan.

ABSTRACT
Objective
To clarify the direct effect of Tacrolimus (FK506) on T cell function in relation to CD29.

Methods
Human T cell line H9 and phytohemagglutinin (PHA)-activated T cells were incubated with or without Tacrolimus. The cells underwent cell migration assay by using fibronectin-coated trans-wells, and at the same time the degree of adherence by cultured cells to fibronectin-coated plastic wells was measured. For H9 cells, intracellular filamentous actin formation and the cell surface expression of CD3, CD11a, CD25, CD26, CD44, CD29 were measured by using flow cytometry. Intracellular tyrosin-phosphorylation induced by fibronectin by CD29 stimulation in H9 cells was analyzed by immunoblotting.

Results
The ability of H9 cells and PHA-activated T cells incubated with Tacrolimus for 2 hours (hrs) to migrate and to adhere to fibronectin was significantly suppressed. However, the inhibiton was transient, because the ability of cells incubated with Tacrolimus for 24 hrs to migrate was not affected despite the suppression of cell replication. Tacrolimus showed slight but significant reduction of cell surface expression of CD29 within 4 hrs, but CD3, CD11a, CD25, CD26 and CD44 were not affected. Tacrolimus rapidly inhibited intracellular filamentous actin formation; the maximum inhibition was within 2 hrs and the effect was not observed at 6 hrs. Intracellular tyrosin-phosphorylation induced by CD29 stimulation was also inhibited by Tacrolimus in H9 cells.

Conclusion
Tacrolimus appeared to have transient early phase inhibitory effects on CD29-related function that may be associated with T cell migration.

Key words
Tacrolimus, T cell, H9, CD29, fibronectin, migration.

This study was supported by a grant from "Japan Research Foundation for Clinical Pharmacology".
Please address correspondence and reprint requests to: Yasuhiko Munakata, MD, Division of Rheumatology & Hematology, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan.
E-mail: mnkt@mail.tains.tohoku.ac.jp