[Proliferation of CD4+ CD25+ regulatory T cells of rat by different cytokines in vitro].
OBJECTIVE
To evaluate the effects of cytokines on the proliferation and function of CD4+ CD25+ regulatory T cell (Treg).


METHODS
Tregs were isolated from naive C57BL/6 mice spleen and lymph nodes. Mature dendritic cells (mDC) were isolated from DBA/2 mice, co-cultured with Tregs, and divided into 4 groups with or without interleukin-2 (IL-2), interleukin-4 (IL-4), and interleukin-15 (IL-15) added into the culture fluid. Fluorescence-activated cell sorting (FACS) was used to detect the Treg proliferation and apoptosis with CFSE and annexin-V staining. The co-culture increased Tregs were divided into 5 groups: CFSE labeled naïve CD4+ CD25- T cells, self-proliferated Treg, Treg mixedly cultured with IL-2 mDC, and Teff, Treg mixedly cultured with IL-4, mDC, and Teff, and Treg mixedly cultured with IL-15, mDC, and Teff, a control group included Teff co-cultured with mDC. FACS was used 5 d later to evaluate the suppressive function of the Treg on the Teff. The expression of Foxp3, indicating the phenotype of Treg was detected.


RESULTS
FASC showed that the values of precursor frequency (PF) of the Tregs stimulated by IL-2, IL-4, and IL-15 were 31.3%, 28.9%, and 34.5% respectively, all significantly higher than that of the control group (14.5% all P < 0.05), and the values of proliferation index (PI) of the Tregs stimulated by IL-2, IL-4, and IL-15 were 1.9, 1.7, and 1.8 respectively, all significantly higher than that of the control group (1.5, all P < 0.05). The apoptotic rates of the Tregs stimulated by IL-2, IL-4, and IL-15 were 12. 8% , 11.4%, and 12.7% respectively, all significantly lower than that of the control group (28.9%, P < 0.05). The Foxp3 expression rate of the Tregs stimulated by IL-2, IL-4, and IL-15 was 91.75%.


CONCLUSIONS
IL-2, IL-4, and IL-15 in the in vitro culture of Treg stimulate the Treg proliferation, reduce their apoptosis, and maintain their suppressive function. The proliferated Tregs still maintain their phenotype, highly expressing Foxp3.
Wang
Zi-Han
ZH
Peking University People's Hospital, Department of Hepatobiliary Surgery, Beijing 100044, China.
Zhu
Ji-Ye
JY
Li
Tao
T
Leng
Xi-Sheng
XS