FJK-16s antibody reacts with mouse/rat Foxp3 (also known as forkhead box P3, SCURFIN and JM2) ; Cross-reactivity of this antibody with other proteins has not been determined. Foxp3, a 49-55 kDa protein, a member of the forkhead/winged helix family of transcriptional regulators, was identified as a genetic defect in scurfy (sf) mice. Foxp3 mRNA has been shown to be constitutively expressed at high levels in CD4+CD25+ regulatory T cells (Treg cells), and ectopic expression of Foxp3 in CD4+CD25- cells produces a Treg phenotype in these cells.

Immunoblotting with FJK-16s antibody has mapped the epitope to amino acids 75-125 of the mouse Foxp3 protein. In humans, alternative splicing in this region has been demonstrated at the mRNA level. Both alternatively spliced and non-spliced isoforms exist in the CD4+CD25+ subset of lymphocytes. Preliminary RT-PCR experiments have not identified this alternative splicing isoform in mouse splenocytes, suggesting that gene regulation differs in mice and humans.

Intracellular staining of mouse splenocytes using FJK-16s using the Mouse Foxp3 Staining Kit and Protocol shows approximately 2% of total splenocytes in the C57Bl/6 strain and the BALB/c mouse strain Approximately 3-5% of total splenocytes were stained. Multicolor flow cytometry analysis demonstrated that approximately 90% of CD4+CD25+ cells and 4% of CD4+CD25- cells were stainable with FJK-16s. B220+, CD11b+, CD11c+, and Ly6G/Gr-1+ cells have not been shown to co-stain with FJK-16s. These data are consistent with a recent report using a GFP knock-in to express Foxp3 (Fontenot et al., 2005).

FJK-16s cross-reacts with rat Foxp3. This was demonstrated by intracellular staining of Foxp3 and flow cytometric analysis of rat splenocytes using the same methods and reagents used for mouse tissue. Please note that the CD4 and CD25 antibodies included in this kit only recognize mouse antigens. For rat tissue staining, use (CD4 FITC, Catalog No. 11-0040 and CD25 PE, Catalog No. 12-0390)

An anti-mouse Foxp3 staining kit has been formulated and optimized for use with FJK-16s single Clonal antibodies stained mouse splenocytes.

Excludes:
Anti-CD4 Isotype Control (Rat IgG2a, Catalog No. 11-4321) and Anti-CD25 (Rat IgG1, Catalog No. 12-4301)

Host
Rat

Isotype
IgG2a

Reactivity/Species
Mouse

Reported application
Intracellular staining followed by flow cytometric analysis