A Cre-driven allele-conditioning line to interrogate CD4+ conventional T cells

Immunity. 2021 Oct 12;54(10):2209-2217.e6. doi: 10.1016/j.immuni.2021.08.029. Epub 2021 Sep 21.


CD4+ T cells share common developmental pathways with CD8+ T cells, and upon maturation, CD4+ T conventional T (Tconv) cells lack phenotypic markers that distinguish these cells from FoxP3+ T regulatory cells. We developed a tamoxifen-inducible ThPOKCreERT2.hCD2 line with Frt sites inserted on either side of the CreERT2-hCD2 cassette, and a Foxp3Ametrine-FlpO strain, expressing Ametrine and FlpO in Foxp3+ cells. Breeding these mice resulted in a CD4conviCreERT2-hCD2 line that allows for the specific manipulation of a gene in CD4+ Tconv cells. As FlpO removes the CreERT2-hCD2 cassette, CD4+ Treg cells are spared from Cre activity, which we refer to as allele conditioning. Comparison with an E8IiCreERT2.GFP mouse that enables inducible targeting of CD8+ T cells, and deletion of two inhibitory receptors, PD-1 and LAG-3, in a melanoma model, support the fidelity of these lines. These engineered mouse strains present a resource for the temporal manipulation of genes in CD4+ T cells and CD4+ Tconv cells.

Keywords: CD4; CD8; T cells; Treg; allele-conditioning; gene editing.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Animals
  • CD4-Positive T-Lymphocytes / cytology*
  • CD8-Positive T-Lymphocytes / cytology
  • Cell Differentiation / immunology*
  • Cell Line
  • Cell Lineage / immunology*
  • Gene Editing / methods*
  • Integrases / genetics*
  • Mice


  • Cre recombinase
  • Integrases