[Frontiers in Bioscience 11, 1360-1370, May 1, 2006]

[Frontiers in Bioscience 11, 1360-1370, May 1, 2006]

Dendritic Cells and CD4⁺CD25⁺ T Regulatory Cells: Crosstalk Between Two Professionals in Immunity versus Tolerance

WanJun Chen

Mucosal Immunology Unit, Oral Infection and Immunity Branch, National Institute of Dental and Craniofacial Research,

National Institutes of Heath, 30, Convent Dr. Bethesda, MD 20892

TABLE OF CONTENTS

1. Abstract
2. DCs
3. CD4⁺CD25⁺ T regs: 3.1. Mechanism(s) of suppression by CD4⁺CD25⁺ T regs; 3.2. Generation of CD4⁺CD25⁺ T regs
4.Role of DCs in the induction/expansion of CD4⁺CD25⁺ T regs
5. DC regulation of suppressive activity of CD4⁺CD25⁺ T regs
6. CD4⁺CD25⁺ T cell regulation of DC function
7. TGF beta: a mediator of crosstalk between DCs and CD4⁺CD25⁺ T regs?
8. Summary
9. Acknowledgment
10. References

1. ABSTRACT

Dendritic cells (DCs) are professional antigen presenting cells (APCs). CD4⁺CD25⁺T regulatory cells (T regs) are recognized as professional regulatory cells. DCs not only initiate T cell immunity by uptake, processing and presentation of specific antigens, but also induce immune tolerance by deletion of T cells and/or induction of regulatory T cells. CD4⁺CD25⁺ T regs maintain immune tolerance by suppressing the function of CD4⁺ and CD8⁺ T cells, B cells, macrophages, DCs and NK cells. It would be inconceivable that the delicate balance between immunity and tolerance could be kept impeccable without the crosstalk between DCs and CD4⁺CD25⁺ T regs. This review focuses on the recent development in our understanding of DCs and CD4⁺CD25⁺ T regs in immune tolerance, with transforming growth factor-beta (TGF-b) serving as a potential link between these two professionals.