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Peripheral CD4(+)CD8(+) T cells are differentiated effector memory cells with antiviral functions.
Michelina Nascimbeni1, Eui-Cheol Shin, Luis Chiriboga
1Liver Diseases Section, DDB, NIDDK, National Institutes of Health, DHHS 10 Center Drive, Bldg 10, Room 9B16, Bethesda, MD 20892-1800, USA.
Blood
|March 27, 2004
Summary
The study reveals that CD4(+)CD8(+) T cells are mature effector cells involved in fighting viral infections. These cells show enhanced proliferation and a differentiated phenotype, contributing to adaptive immunity against pathogens.
Area of Science:
- Immunology
- Virology
- Cell Biology
Background:
- The role of CD4(+)CD8(+) T cells in viral infections is not well understood.
- Increased frequencies of these cells are observed in peripheral blood during viral infections.
Purpose of the Study:
- To investigate the function and biological significance of circulating CD4(+)CD8(+) T cells.
- To determine if these cells are involved in adaptive immune responses to viral pathogens.
Main Methods:
- Analysis of peripheral blood T cells from viral infection patients.
- In vitro antigenic challenge and proliferation assays.
- Ex vivo characterization of T cell phenotype, T-cell receptor excision circles (TREC) content, and telomere length.
- Detection of CD4(+)CD8(+) T cells at infection sites (liver in chronic hepatitis C).
- Prospective analysis of CD4(+)CD8(+) T cell frequency and viral kinetics in a chimpanzee model of Hepatitis C Virus (HCV) infection.
Main Results:
- Circulating CD4(+)CD8(+) T cells are mature effector memory lymphocytes specific for multiple viral antigens.
- These cells exhibit a T helper 1/T cytotoxic 1 (Th1/Tc1) cytokine profile and proliferate more upon antigenic challenge compared to single-positive T cells.
- CD4(+)CD8(+) T cells show a differentiated phenotype, with lower TREC content and shorter telomeres, indicating prior cell division.
- Tissue-homing marker CXCR3 expression confirms CD4(+)CD8(+) T cell presence at sites of persistent viral infection.
- A strong correlation was observed between activated CD4(+)CD8(+) T cell frequency and viral kinetics in HCV infection.
Conclusions:
- Peripheral CD4(+)CD8(+) T cells are active participants in the adaptive immune response against infectious pathogens.
- These findings expand the understanding of T cell populations involved in antiviral immunity.
- CD4(+)CD8(+) T cells represent a crucial component of the immune surveillance against persistent viral infections.