Foxp3-IRES-mRFP (FIR) Reporter Mouse to Monitor Treg Activity

Applications: Immuno-oncology and autoimmunity

This reliable Foxp3 reporter mouse model allows you to efficiently monitor and sort Foxp3-expressing cells from different lymphocyte lineages and lymphoid organs, and represents a powerful drug testing tool to:

  • Study the modulation of the immune tolerance mechanism in autoimmune diseases
  • Treat cancers via immune checkpoint inhibitor discovery

Model features:

  • Physiological expression of Foxp3
  • mRFP reporter faithfully mirrors Foxp3 expression


The model is widely used and validated, with more than 50 publications available from independent renowned laboratories.

Original reference:
Wan YY; Flavell RA. 2005. Identifying Foxp3-expressing suppressor T cells with a bicistronic reporter. Proc Natl Acad Sci U S A 102(14):5126-31. [PubMed]

Additional References


Gutcher I; Donkor MK; Ma Q; Rudensky AY; Flavell RA; Li MO. 2011. Autocrine Transforming Growth Factor-beta1 Promotes In Vivo Th17 Cell Differentiation. Immunity 34(3):396-408. [PubMed]


Chae WJ; Gibson TF; Zelterman D; Hao L; Henegariu O; Bothwell AL. 2010. Ablation of IL-17A abrogates progression of spontaneous intestinal tumorigenesis. Proc Natl Acad Sci U S A 107(12):5540-4. [PubMed]

Hawiger D; Wan YY; Eynon EE; Flavell RA. 2010. The transcription cofactor Hopx is required for regulatory T cell function in dendritic cell-mediated peripheral T cell unresponsiveness. Nat Immunol 11(10):962-8. [PubMed]

Lin PY; Sun L; Thibodeaux SR; Ludwig SM; Vadlamudi RK; Hurez VJ; Bahar R; Kious MJ; Livi CB; Wall SR; Chen L; Zhang B; Shin T; Curiel TJ. 2010. B7-H1-dependent sex-related differences in tumor immunity and immunotherapy responses. J Immunol 185(5):2747-53. [PubMed]

Ouyang W; Beckett O; Ma Q; Paik JH; DePinho RA; Li MO. 2010. Foxo proteins cooperatively control the differentiation of Foxp3+ regulatory T cells. Nat Immunol 11(7):618-27. [PubMed]

Ouyang W; Beckett O; Ma Q; Li MO. 2010. Transforming growth factor-beta signaling curbs thymic negative selection promoting regulatory T cell development. Immunity 32(5):642-53. [PubMed]

Schreiber TH; Wolf D; Tsai MS; Chirinos J; Deyev VV; Gonzalez L; Malek TR; Levy RB; Podack ER. 2010. Therapeutic Treg expansion in mice by TNFRSF25 prevents allergic lung inflammation. J Clin Invest 120(10):3629-40. [PubMed]

Wang Y; Souabni A; Flavell RA; Wan YY. 2010. An intrinsic mechanism predisposes foxp3-expressing regulatory T cells to th2 conversion in vivo. J Immunol 185(10):5983-92. [PubMed]


Kriegel MA; Rathinam C; Flavell RA. 2009. E3 ubiquitin ligase GRAIL controls primary T cell activation and oral tolerance. Proc Natl Acad Sci U S A 106(39):16770-5. [PubMed]

Long M; Park SG; Strickland I; Hayden MS; Ghosh S. 2009. Nuclear factor-kappaB modulates regulatory T cell development by directly regulating expression of Foxp3 transcription factor. Immunity 31(6):921-31. [PubMed]

Ouyang W; Beckett O; Flavell RA; Li MO. 2009. An essential role of the Forkhead-box transcription factor Foxo1 in control of T cell homeostasis and tolerance. Immunity 30(3):358-71. [PubMed]


Li MO; Wan YY; Flavell RA. 2007. T cell-produced transforming growth factor-beta1 controls T cell tolerance and regulates Th1- and Th17-cell differentiation. Immunity 26(5):579-91. [PubMed]

Wan YY; Flavell RA. 2007. Regulatory T-cell functions are subverted and converted owing to attenuated Foxp3 expression. Nature 445(7129):766-70. [PubMed]

Yamazaki S; Bonito AJ; Spisek R; Dhodapkar M; Inaba K; Steinman RM. 2007. Dendritic cells are specialized accessory cells along with TGF- for the differentiation of Foxp3+ CD4+ regulatory T cells from peripheral Foxp3 precursors. Blood 110(13):4293-302. [PubMed]


Kamanaka M; Kim ST; Wan YY; Sutterwala FS; Lara-Tejero M; Galan JE; Harhaj E; Flavell RA. 2006. Expression of interleukin-10 in intestinal lymphocytes detected by an interleukin-10 reporter knockin tiger mouse. Immunity 25(6):941-52. [PubMed]


Model validation

Foxp3 is the regulatory T cell-specific transcription factor that functions as the master regulator of the development and function of regulatory T cells.
This Foxp3-IRES-mRFP (FIR) mouse model provides access to direct in vivo detection of Foxp3-expressing cells.

In contrast to other existing Foxp3 models generated by random insertion, this Knockin mouse line preserves physiological expression of Foxp3 and enables monitoring of endogenous Foxp3.

No deregulation of endogenous Foxp3 expression:

  • Endogenous Foxp3 is expressed and functional: reporter gene inserted in the 3'UTR of the endogenous Foxp3 locus
  • The genetic manipulation inserted is controlled
  • Reporter faithfully mirrors Foxp3 expression

Suitable model for your Treg studies:

  • Foxp3-expressing cells can be directly detected by monitoring mRFP expression (Fig. 1)
  • Uncompromised immune system: intact function of Treg cells (Fig. 2)
  • Optimum monitoring of Treg cells trafficking and cell sorting
Fig. 1) mRFP expression correlates with Foxp3-expressing T cells in vivo. Figure 1 - Foxp3-IRES-mRFP FIR Reporter Mouse
Left panel: Foxp3 expression was detected in peripheral lymphocytes from Foxp3-IRES-mRFP mice harvested and stained with fluorophore-conjugated anti-CD4 and anti-CD25 antibodies. mRFP expression in CD4 T cells was monitored by flow cytometry.

Right panel: RNA was extracted from different populations of peripheral CD4 T cells purified from FIR mice by FACS. Relative mRNA levels of Foxp3 were determined by TaqMan real-time quantitative PCR, and combined results of two experiments were plotted.
Fig. 2) mRFP expression does not compromise the regulatory activity of Foxp3-expressing T cells in vivo. Figure 2 - Foxp3-IRES-mRFP FIR Reporter Mouse
The immunosuppressive function of Foxp3-expressing cells is not impaired when mRFP is co-expressed.
CD4+mRFP+ suppressor (S) and CD4+CD25-mRFP- responder (R) T cells were purified by FACS. Suppressor and responder cells were either cultured alone or mixed at indicated ratios (R:S), whereas the number of responder cells remained the same. T cells were activated by soluble anti-CD3 and anti-CD28 antibodies in the presence of irradiated APCs. Three days after stimulation, T cell proliferation was measured by a [3H]thymidine incorporation assay.


Ready to be shipped to your lab

  • Cohorts available upon request
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  • Models provided with FTO on patent-protected technologies used for model generation