Flow Cytometric Profiling of Mature and Developing Regulatory T Cells in the Thymus
Natural Regulatory T (Treg) cells are a subset of CD4+ T cells characterized by expression of the transcription factor Foxp3 and the ability to suppress immune responses. Treg cells develop in the thymus in response to highly specific interactions between the T cell receptor (TCR) and self-antigens. These processes can be recapitulated in antigen-specific systems using transgenic mice that coexpress a TCR with its cognate peptide as a neoself-antigen. Here, we describe a method for using such a system to establish a flow cytometric profile of phenotype markers expressed by developing and mature Treg cells in the thymus. Our approach is to compare antigen-specific thymocytes developing in the presence or absence of Treg cell-selecting ligands to identify phenotypic changes that characterize thymocytes undergoing selection into the Treg cell lineage.
Key wordsThymocyte Foxp3 Immune regulation Treg progenitor cell Immunophenotyping
The authors would like to thank Malinda Aitken, Christina Mergenthaler, Abigail Liebow, Alissa Basehoar, and Lori Mroz for their invaluable help in maintaining the transgenic mouse lineages described here. This work was supported by R01-AI59166 and by the Commonwealth Universal Research Enhancement Program, Pennsylvania department of Health. DMS is supported by T32 CA09171.