CD8(+) T-cell selection, function, and death in the primary immune response in vivo

Area of Science:

• Immunology
• Virology
• Cellular Biology

Background:

• The primary immune response to Epstein Barr virus (EBV) involves significant expansion of EBV-specific CD8(+) T cells.
• Understanding the clonal dynamics and functional characteristics of these T cells is crucial for comprehending immune regulation and memory formation.

Purpose of the Study:

• To investigate the clonal composition and functional properties of CD8(+) T cells during the primary EBV immune response.
• To analyze the mechanisms controlling the downregulation of the primary response and the selection of memory T cells.

Main Methods:

• Analysis of clonal composition of T cells mediating the primary response.
• Assessment of functional properties, including cytotoxicity and cytokine secretion, of virus-specific T cells.
• Investigation of programmed cell death pathways and their role in regulating T cell populations.

Main Results:

• Massively expanded T cell clones dominate the primary EBV-specific T cell response.
• Virus-specific T cells are highly cytotoxic but functionally heterogeneous, with some subpopulations being hyporesponsive to cytokines.
• The majority of primary response cells undergo cytokine-rescuable programmed cell death, leading to a small, selected memory T cell population.
• Clones dominant in the primary response are significantly reduced during memory cell establishment.

Conclusions:

• The primary EBV immune response is characterized by clonal expansion and functional heterogeneity of CD8(+) T cells.
• Programmed cell death plays a critical role in regulating the magnitude of the primary response and shaping the memory T cell pool.
• The selection process for memory T cells involves culling of clones that were dominant during the acute phase of infection.