Generation and biochemical analysis of human effector CD4 T cells: alterations in tyrosine phosphorylation and loss of CD3 zeta expression

作者：Krishnan S; Warke VG; Nambiar MP; Wong HK; Tsokos GC; Farber DL^*

来源：Blood, 2001, 97(12): 3851-3859.

DOI：10.1182/blood.V97.12.3851

Human effector T cells have been difficult to Isolate and characterize due to their phenotypic and functional similarity to the memory subset, In this study, a biochemical approach was used to analyze human effector CD4 T cells generated in vitro by activation with anti-CD3 and autologous monocytes for 3 to 5 days. The resultant effector cells expressed the appropriate activation/differentiation markers and secreted high levels of interferon gamma (IFN-gamma) when restimulated. Biochemically, effector CD4 T cells exhibited increases in total intracellular tyrosine phosphorylation and effector-associated phosphorylated species. Paradoxically, these alterations in tyrosine phosphorylation were concomitant with greatly reduced expression of CD3 zeta and CD3 epsilon signaling subunits coincident with a reduction in surface T-cell receptor (TCR) expression. Because loss of CD3 zeta has also been detected in T cells isolated ex vivo from individuals with cancer, chronic viral infection, and autoimmune diseases, the requirements and kinetics of CD3 zeta down-regulation were examined. The loss of CD3 zeta expression persisted throughout the course of effector T-cell differentiation, was reversible on removal from the activating stimulus, and was modulated by activation conditions. These biochemical changes occurred in effector T cells generated from naive or memory CD4 T-cell precursors and distinguished effector from memory T cells. The results suggest that human effector T-cell differentiation is accompanied by alterations in the TCR signal transduction and that loss of CD3 zeta expression may be a feature of chronic T-cell activation and effector generation in vivo.

• 出版日期2001-6-15