Subsets of nonclonal neighboring CD4+ T cells specifically regulate the frequency of individual antigen-reactive T

Nevil J Singh1, Jennifer K Bando, Ronald H Schwartz

  • 1Laboratory of Cellular and Molecular Immunology, NIAID, NIH, Bethesda, MD 20892, USA. ns117r@nih.gov

Immunity
|October 2, 2012
PubMed

After an immune response, the expanded population of antigen-specific CD4(+) T cells contract to steady state levels. We have found that the contraction is neither cell-autonomous nor mediated by competition for generic trophic factors, but regulated by relatively rare subsets of neighboring CD4(+) T cells not necessarily of a conventional regulatory T cell lineage. These regulators, referred to as deletors, specifically limit the frequency of particular antigen-specific T cells even though they are not reactive to the same agonist as their targets. Instead, an isolated deletor could outcompete the target for recognition of a shared, nonstimulatory endogenous peptide-MHC ligand. This mechanism was sufficient to prevent even agonist-driven autoimmune disease in a lymphopenic environment. Such a targeted regulation of homeostasis within narrow colonies of T cells with related TCR specificities for subthreshold ligands might help to prevent the loss of unrelated TCRs during multiple responses, preserving the valuable diversity of the repertoire.

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