Abstracts (complete list) - Wissenschaft Online

Xuefang Ren, Marion Schneider, Ying Wang, Lin Xu, Zhenggang Jiang, Fei Ye
Activation induced cell death of CD4+CD25+Foxp3+ T cells by
TCR re-stimulation involves a CD95/CD95L dependent
mechanism
In order to better understand how regulatory T cells (Treg) would be modulated, we
isolated murine CD4+CD25+T cells from naive BALB/c or DO11.10 mice by MACS
(magnetic cell sorting). Treg were functionally verified by suppressing an 3H cell
proliferation assay. RT-PCR and intracellular staining were applied to detect the
expression of Foxp3 in these cells. To induce actvation induced cell death (AICD), Treg
from BALB/c mice were stimulated with anti-CD3/CD28 antibodies, and those from
DO11.10 mice were incubated with OVA323-339 peptide plus antigen presenting cells
(APCs), respectively. SuperArray and Real-time PCR were established to detect the
apoptosis gene expression pattern in Treg. Flow cytometry was performed to determine
the apoptosis of Treg. The influence of anti-FasL, anti-TRAIL neutralizing antibody and
zVAD-fmk on AICD of Treg was evaluated.
Results: CD4+CD25+Foxp3+ Treg act to suppress activation of the immune system and
thereby maintain immune system homeostasis and tolerance to self. Management of
Treg during an immune response is very significant. To augment Treg is advantageous
in autoimmune disease, allergy and organ transplantation. On the contrary, depletion of
Treg is beneficial to cancer patients. Activation induced cell death (AICD) is one of the
main mechanisms for T cell contraction in vivo. We show here CD4+CD25+T cells from
murine splenocytes could be successfully classified by MACS with 98% purity and
specifically express Foxp3 which is the ‘master control gene’ for Treg cells and
demonstrated suppression of proliferation of CD4+CD25-T cells. Treg can be induced to
AICD by TCR re-stimulation, which may reach up to 39-45• following in vitro
activationfor 7 days. The results of SuperArray and real-time PCR showed different gene
expression patterns of TNF family members in freshly isolated Treg and activated Treg.
TCR re-stimulation of Treg in vitro revealed a CD95/CD95L dependent pathway toward
AICD. These findings open up to more detailed investigation of Treg modulatory events
in vivo.