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The molecular program induced in T cells undergoing homeostatic proliferation
Ananda W Goldrath1, C John Luckey, Richard Park
1Section on Immunology and Immunogenetics, Joslin Diabetes Center, and Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, One Joslin Place, Boston, MA 02215, USA.
Summary
Naïve T cells undergo antigen-independent proliferation in lymphopenic environments, driven by specific intracellular signals. This process leads to differentiation into authentic memory T cells, not a unique cell type.
Area of Science:
- Immunology
- Cell Biology
Background:
- Naïve T cells can proliferate without foreign antigen recognition when the immune system experiences lymphopenia.
- This lymphopenia-induced proliferation is known to be dependent on low-affinity MHC/self-peptide complexes and IL-7 signaling.
Purpose of the Study:
- To investigate the intracellular signaling pathways and gene expression changes governing T cell proliferation in lymphopenic hosts.
- To determine if antigen-independent proliferation leads to a distinct T cell phenotype or differentiation into memory cells.
Main Methods:
- Analysis of gene expression profiles in naïve CD8+ T cells at various time points after transfer into lymphopenic environments.
- Comparison of gene expression patterns with those induced by full antigenic stimulation.
Main Results:
- Lymphopenia induced an attenuated subset of genes typically upregulated during full antigenic stimulation, focusing on cell cycling genes and excluding effector activity genes.
- Following initial proliferation, T cells in lymphopenic hosts adopted a stable gene expression pattern resembling antigen-experienced memory cells.
Conclusions:
- Antigen-independent T cell proliferation in lymphopenic hosts relies on established intracellular signaling pathways, not unique molecular signatures.
- This proliferation ultimately results in the differentiation of naïve T cells into authentic memory T cells.