Related Experiment Videos
Antigen-independent changes in naive CD4 T cells with aging
P J Linton1, L Haynes, N R Klinman
1Sidney Kimmel Cancer Center, San Diego, California 92121, USA.
The Journal of Experimental Medicine
|November 1, 1996
Summary
Aging immune systems show a shift in CD4+ T cells towards a memory phenotype. This shift is antigen-dependent, but intrinsic aging also impacts naive T cell function.
Area of Science:
- Immunology
- Aging research
- T cell biology
Background:
- The elderly experience a significant change in CD4+ T cell populations, characterized by an increase in memory phenotype cells with reduced responsiveness.
- Understanding the role of environmental antigen exposure versus intrinsic aging is crucial for explaining these changes.
Purpose of the Study:
- To investigate whether the aged CD4+ T cell phenotype is driven by environmental antigen exposure or intrinsic aging processes.
- To differentiate between antigen-dependent and antigen-independent alterations in CD4+ T cells during aging.
Main Methods:
- Analysis of CD4+ T cells from aged T cell receptor (TCR) transgenic (Tg) mice, where environmental antigen exposure is controlled.
- Phenotypic analysis (CD44, CD45RB) and functional assessment (cytokine secretion, proliferation, co-stimulation requirements) of transgene-positive (Tg+) and transgene-negative (Tg-) CD4+ T cells.
Main Results:
- Aged TCR Tg+ CD4+ T cells, despite reduced numbers and responsiveness, retained a naive phenotype (CD44lo CD45RBhi).
- The proportion of transgene-negative (Tg-) CD4+ T cells increased and exhibited an aged, memory phenotype.
- Antigenic stimulation of Tg+ cells resulted in IL-2 secretion and required co-stimulation for proliferation, consistent with naive cells.
Conclusions:
- The shift towards a memory phenotype in aging CD4+ T cells is significantly influenced by antigenic stimulation.
- Intrinsic aging processes independently reduce the responsiveness of naive CD4+ T cells, affecting cytokine secretion and proliferative capacity.