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.
Teng
Lichen
L
Department of Organ Transplantation, First Affiliated Hospital, Sun Yat-sen University, Guangzhou City, China.
Liu
Longshan
L
Su
Yajuan
Y
Yuan
Xiaopeng
X
Li
Jun
J
Fu
Qian
Q
Chen
Siyang
S
Wang
Changxi
C
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