Peripheral blood T regulatory cell counts may not predict transplant rejection.
BACKGROUND
Recent evidence shows that allograft survival rates show a positive correlation with the number of circulating T regulatory cells (Tregs). This study investigated both the number and the cytokine profiles exhibited by Foxp3+ Tregs in blood, spleen and lymph nodes of Lewis rat recipients of BN rat cardiac allografts after a single-dose of Rapamycin (RAPA).


RESULTS
Rats were divided into three groups: control group (containing healthy control and acute rejection group), and recipients treated with a single dose of RAPA on either Day 1 (1D group)or Day 3 (3D group) post-transplant. We analyzed the number of Foxp3+Tregs and the expression of Foxp3 and cytokines in the peripheral blood and the peripheral lymphoid tissues. No difference was found in the numbers of circulating Foxp3+ Tregs between these three groups. RAPA administration significantly increased Foxp3 expression in peripheral lymphoid tissues after a single dose of RAPA on Day 3 post-transplant. Foxp3+Tregs inhibited the activity of effector T cells (Teff) via the secretion of TGF-beta1.


CONCLUSIONS
The number of Tregs in the recipient's blood may not be a good predictor of transplant rejection. Foxp3+Tregs inhibit the activity of Teff cells mainly in the peripheral lymphoid tissues.
Huang
Yuchuan
Y
Key Laboratory of Transplant Engineering and Immunology, Ministry of Health, West China Hospital, Sichuan University, Chengdu China. huangyuchuan1999@yahoo.com.cn
Shan
Juan
J
Zhang
Chuntao
C
Zhang
Jie
J
Feng
Li
L
Li
Shengfu
S
Li
Youping
Y
D000818:Animals; D018791:CD4 Lymphocyte Count; D051858:Forkhead Transcription Factors / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006084:Graft Rejection / Q000276:immunology*; D006085:Graft Survival / Q000187:drug effects / Q000276:immunology; D016027:Heart Transplantation / Q000276:immunology*; D016753:Interleukin-10 / Q000235:genetics / Q000378:metabolism; D008198:Lymph Nodes / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D018448:Models, Immunological; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020123:Sirolimus / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology; D013154:Spleen / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D050378:T-Lymphocytes, Regulatory / Q000166:cytology* / Q000276:immunology*; D013997:Time Factors; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism; D014184:Transplantation, Homologous
D051858:Forkhead Transcription Factors; C500522:Foxp3 protein, rat; D012333:RNA, Messenger; D053773:Transforming Growth Factor beta1; D016753:Interleukin-10; D020123:Sirolimus