Differential effect of calcineurin inhibitors, anti-CD25 antibodies and rapamycin on the induction of FOXP3 in human T cells.
BACKGROUND
The transcription factor FOXP3 has been identified as the molecule associated with the regulatory function of CD25+ T cells.


METHODS
To understand the biology of FOXP3+ T cells in allogeneic reactions, we measured FOXP3 mRNA expression levels in allostimulated CD25 cells and CD25 cells and in peripheral blood mononuclear cells (PBMC). The effect of immunosuppressive drugs on FOXP3 expression was studied in mixed lymphocyte reactions (MLR) in the presence and absence of calcineurin inhibitors (CNI), alphaCD25 mAb, and Rapamycin (Rapa), and analyzed in biopsies from cardiac allograft recipients during acute rejection by quantitative (Q)-PCR.


RESULTS
FOXP3 mRNA expression was restricted to the CD25 population that inhibited the proliferation of allostimulated CD25 cells. In the MLR FOXP3 was readily induced after allostimulation. Kinetic examination of the MLR showed a 10-20-fold higher FOXP3 mRNA expression level after 5 days of culture. The CNI Cyclosporin and Tacrolimus, and alphaCD25 mAb inhibited in vitro induced FOXP3 gene transcription (range 70%-90%), whereas Rapa did not inhibit the induction. After clinical heart transplantation the highest FOXP3 mRNA expression levels were measured in biopsies during acute rejection (P=0.03).


CONCLUSIONS
The high FOXP3 mRNA levels during allogeneic responses in vivo and in vitro suggests that regulatory activities of CD25 T cells or the generation of these cells is an intrinsic part of activation. CNI and alphaCD25 mAb in contrast to Rapa, did interfere with this immunosuppressive counter-mechanism and as a result might have an inhibitory effect to tolerance induction after transplantation.
Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, The Netherlands. c.c.baan@erasmusmc.nl
Carla C
CC
Baan
Barbara J
BJ
van der Mast
Mariska
M
Klepper
Wendy M
WM
Mol
Annemiek M A
AM
Peeters
Sander S
SS
Korevaar
Aggie H M M
AH
Balk
Willem
W
Weimar
D001483:Base Sequence; D065095:Calcineurin Inhibitors; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000276:immunology*; D051858:Forkhead Transcription Factors; D005786:Gene Expression Regulation / Q000276:immunology; D006084:Graft Rejection / Q000276:immunology; D016027:Heart Transplantation / Q000276:immunology*; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007959:Lymphocyte Culture Test, Mixed; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000235:genetics; D015375:Receptors, Interleukin-2 / Q000276:immunology*; D020123:Sirolimus / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D014158:Transcription, Genetic; D014184:Transplantation, Homologous / Q000276:immunology
D065095:Calcineurin Inhibitors; D017931:DNA Primers; D004268:DNA-Binding Proteins; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; D007166:Immunosuppressive Agents; D012333:RNA, Messenger; D015375:Receptors, Interleukin-2; D020123:Sirolimus