Suppression of alloimmunity in mice by regulatory T cells converted with conditioned media.
BACKGROUND
Compared with rare CD4+CD25+ regulatory T cells (Tregs), CD4+CD25- T cells are abundant in peripheral blood. Studies have demonstrated that tumors can convert naive CD4+CD25- T cells into CD4+CD25+Foxp3+ Tregs; however, the potential application of the converted Tregs in transplant medicine has not well demonstrated.


METHODS
CD4+CD25- T cells isolated cultured for 5 d in various combinations of cell culture medium and conditioned medium from RenCa cells. Foxp3 levels were determined by flow cytometry and real-time polymerase chain reaction. BALB/c mouse mononuclear cells (responder) combined with different ratios of the converted CD4+CD25+ Tregs were co-cultured with inactivated C57BL/6 mononuclear cells (stimulator) in one-way mixed lymphocyte reaction (MLR). In addition, the converted Tregs were transferred into a mouse skin transplant model, and graft histology, survival time, and delayed-type hypersensitivity were assessed.


RESULTS
CD4+CD25- T cells cultured in media supplemented with increasing concentrations of RenCa conditioned medium were partially converted into CD4+CD25+ Tregs; conversion increased as the percentage of conditioned medium increased. Moreover, the converted CD4+CD25+ Tregs possessed characteristics similar to those of naturally occurring Tregs, including Foxp3 expression and the ability to suppress T cell proliferation in one-way MLR in a concentration-dependent manner. Immunosuppressive effects of the converted CD4+CD25+ Tregs were also similar to those of naturally occurring Tregs in vivo, suppressing allograft rejection and prolonging survival time of allogeneic skin grafts following adoptive transfer in mice (P<0.05).


CONCLUSIONS
Our findings indicate that CD4+CD25- T cells cultured with conditioned media from tumor cells may be useful for obtaining sufficient numbers of Tregs, which may help suppress acute rejection and prolong graft survival.
Department of Organ Transplantation, First Affiliated Hospital, Sun Yat-sen University, Guangzhou City, China.
Lichen
L
Teng
Longshan
L
Liu
Yajuan
Y
Su
Xiaopeng
X
Yuan
Jun
J
Li
Qian
Q
Fu
Siyang
S
Chen
Changxi
C
Wang
D019264:Adoptive Transfer; D000818:Animals; D015704:CD4 Antigens / Q000378:metabolism; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000494:pharmacology*; D051858:Forkhead Transcription Factors / Q000378:metabolism; D006085:Graft Survival / Q000276:immunology*; D006968:Hypersensitivity, Delayed / Q000276:immunology*; D007165:Immunosuppression Therapy / Q000379:methods*; D053645:Interleukin-2 Receptor alpha Subunit / Q000378:metabolism; D007680:Kidney Neoplasms; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D016038:Skin Transplantation / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D014184:Transplantation, Homologous / Q000276:immunology
D015704:CD4 Antigens; D017077:Culture Media, Conditioned; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; C508018:Il2ra protein, mouse; D053645:Interleukin-2 Receptor alpha Subunit