Competition for self-peptide-MHC complexes and cytokines between  naïve and memory CD8⁺ T cells espressing the same or different T cell receptors

Speaker:顏廷穎

Commentator:謝奇璋 老師

The number of naïve T cells in the peripheral remains constant.  The proliferation and survival of naïve T cell are regulated by the interaction with self-peptide MHC complex and cytokines. Previous studies showed that naïve CD4⁺ T cells with different TCRs may proliferate without competing for TCR-self-peptide-MHC complexes.  Naïve and memory T cells exist in the same place. Previous studies showed that both naïve and memory T cells need self-peptide MHC complex to maintain their functional properties and IL-7 to survival.  In this study, the authors investigated if there is any competition between naïve and memory T cells.  They used transgenic mice which had restricted TCR on naive T cells to design the experiments.  They found that the proliferation of transferred naïve T cell was limited in the host whose T cells expressed the same TCR.  This phenomenon may depend on the relative strength of the TCR-self-peptide MHC interaction and cytokines, but this was not so critical in the host whose memory T cells harbor different TCR.  Their data showed that the competition really existed between naïve and memory T cells.  Naïve and memory CD8⁺ T cells with the same TCR may compete for self-peptide-MHC complexes as well as cytokines for homeostasis.      

References:

1. Troy, A. E. & Shen, H. Cutting Edge: Homeostatic Proliferation of Peripheral T Lymphocytes Is Regulated by Clonal Competition1.(2003) J. Immunol. 170, 672–676.

2. Moses, C.T., Thorstenson, K.M., Jameson, S. C.& khoruts, Competition for self ligands restrains homeostatic proliferation of naive CD4 T cells. (2003) Proc.

Natl. Acad. Sci. USA 100, 1185–1190.

3. Qing G., Ailin B., Brendan J., Herman N. E., & Jianzhu C. Competition for self-peptide–MHC complexes and cytokines between naive and memory CD8 T cells expressing the same or different T cell receptors. (2004) Proc.

Natl. Acad. Sci. USA 101, 3041-3046 .