The calcineurin inhibitor tacrolimus allows the induction of functional CD4CD25 regulatory T cells by rabbit anti-thymocyte globulins

Clin Exp Immunol. 2010 Aug;161(2):364-77. doi: 10.1111/j.1365-2249.2010.04183.x. Epub 2010 May 28.


Rabbit anti-thymocyte globulins (rATG) induce CD4(+)CD25(+)forkhead box P3 (FoxP3(+)) regulatory T cells that control alloreactivity. In the present study, we investigated whether rATG convert T cells into functional CD4(+)CD25(+)FoxP3(+)CD127(-/low) regulatory T cells in the presence of drugs that may hamper their induction and function, i.e. calcineurin inhibitors. CD25(neg) T cells were stimulated with rATG or control rabbit immunoglobulin G (rIgG) in the absence and presence of tacrolimus for 24 h. Flow cytometry was performed for CD4, CD25, FoxP3 and CD127 and the function of CD25(+) T cells was examined in suppression assays. MRNA expression profiles were composed to study the underlying mechanisms. After stimulation, the percentage CD4(+)CD25(+)FoxP3(+)CD127(-/low) increased (from 2% to 30%, mean, P < 0.01) and was higher in the rATG samples than in control rIgG samples (2%, P < 0.01). Interestingly, FoxP3(+)T cells were also induced when tacrolimus was present in the rATG cultures. Blockade of the interleukin (IL)-2 pathway did not affect the frequency of rATG-induced FoxP3(+) T cells. The rATG tacrolimus-induced CD25(+) T cells inhibited proliferative responses of alloantigen-stimulated effector T cells as vigorously as rATG-induced and natural CD4(+)CD25(+)FoxP3(+)CD127(-/low) T cells (67% +/- 18% versus 69% +/- 16% versus 45% +/- 20%, mean +/- standard error of the mean, respectively). At the mRNA-expression level, rATG-induced CD25(+) T cells abundantly expressed IL-10, IL-27, interferon (IFN)-gamma, perforin and granzyme B in contrast to natural CD25(+) T cells (all P = 0.03), while FoxP3 was expressed at a lower level (P = 0.03). These mRNA data were confirmed in regulatory T cells from kidney transplant patients. Our findings demonstrate that tacrolimus does not negatively affect the induction, phenotype and function of CD4(+)CD25(+) T cells, suggesting that rATG may induce regulatory T cells in patients who receive tacrolimus maintenance therapy.

MeSH terms

  • Animals
  • Antilymphocyte Serum / immunology*
  • Antilymphocyte Serum / therapeutic use
  • Cell Differentiation / drug effects
  • Cell Differentiation / immunology
  • Cells, Cultured
  • Coculture Techniques
  • Cytotoxicity, Immunologic / immunology
  • Forkhead Transcription Factors / metabolism
  • Gene Expression / genetics
  • Gene Expression / immunology
  • Granzymes / genetics
  • Granzymes / metabolism
  • Humans
  • Immune Tolerance / immunology
  • Interferon-gamma / genetics
  • Interleukin-2 Receptor alpha Subunit / metabolism*
  • Interleukin-7 Receptor alpha Subunit / metabolism
  • Interleukins / genetics
  • Isoantigens / immunology
  • Kidney Transplantation / immunology
  • Lymphocyte Activation / drug effects
  • Lymphocyte Activation / immunology*
  • Minor Histocompatibility Antigens
  • Perforin / genetics
  • Phosphorylation / drug effects
  • Phosphorylation / immunology
  • Rabbits
  • T-Lymphocyte Subsets / cytology
  • T-Lymphocyte Subsets / drug effects
  • T-Lymphocyte Subsets / immunology
  • T-Lymphocyte Subsets / metabolism
  • T-Lymphocytes, Regulatory / cytology
  • T-Lymphocytes, Regulatory / immunology*
  • T-Lymphocytes, Regulatory / metabolism
  • Tacrolimus / pharmacology*
  • Tacrolimus / therapeutic use
  • p38 Mitogen-Activated Protein Kinases / metabolism


  • Antilymphocyte Serum
  • EBI3 protein, human
  • FOXP3 protein, human
  • Forkhead Transcription Factors
  • IL2RA protein, human
  • Interleukin-2 Receptor alpha Subunit
  • Interleukin-7 Receptor alpha Subunit
  • Interleukins
  • Isoantigens
  • Minor Histocompatibility Antigens
  • Perforin
  • Interferon-gamma
  • p38 Mitogen-Activated Protein Kinases
  • Granzymes
  • Tacrolimus