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Continued antigen stimulation is not required during CD4(+) T cell clonal expansion
William T Lee1, Gregory Pasos, Luiza Cecchini
1Laboratory of Clinical and Experimental Immunology and Endocrinology, Wadsworth Center, Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, NY 12201, USA. William.Lee@wadsworth.org
Journal of Immunology (Baltimore, Md. : 1950)
|February 2, 2002
Summary
Antigen (Ag) exposure initiates CD4(+) T cell proliferation. Limited Ag exposure programs cells to divide independently, though Ag enhances T cell survival and total divisions.
Area of Science:
- Immunology
- Cell Biology
Background:
- CD4(+) T cell proliferation is initiated by peptide antigen (Ag).
- The precise role of Ag in subsequent T cell clonal expansion remains incompletely understood.
Purpose of the Study:
- To investigate the long-term effects of initial antigen exposure on CD4(+) T cell proliferation and clonal expansion.
- To determine if continued antigen presence is necessary for sustained T cell division.
Main Methods:
- Murine CD4(+) T cells were labeled with carboxyfluorescein succinimidyl ester (CFSE).
- Cells were stimulated with specific peptide antigen and proliferation was assessed by CFSE dilution.
- Proliferating cells were separated based on CFSE intensity to analyze daughter cell behavior.
Main Results:
- CFSE fluorescence halved with each cell division, confirming T cell activation and proliferation.
- Daughter T cells continued to proliferate even after the removal of the antigen.
- A brief 2-hour exposure to peptide antigen programmed T cells for antigen-independent proliferation.
- Antigen was not essential for cell division but enhanced T cell survival and increased the total number of cell divisions during clonal expansion.
Conclusions:
- Initial antigen exposure initiates a cell division program in CD4(+) T cells.
- This proliferation program can proceed independently of continuous antigen stimulation.
- Further T cell receptor (TCR) stimulation modifies, but is not required for, antigen-driven cell division.