Analysis of FOXP3 protein expression in human CD4+CD25+ regulatory T cells at the single-cell level.
The transcription factor FOXP3 plays a key role in CD4(+)CD25(+) regulatory T cell function and represents a specific marker for these cells. Despite its strong association with regulatory T cell function, in humans little is known about the frequency of CD4(+)CD25(+) cells that express FOXP3 protein nor the distribution of these cells in vivo. Here we report the characterization of seven anti-FOXP3 monoclonal antibodies enabling the detection of endogenous human FOXP3 protein by flow cytometry and immunohistochemistry. Flow-cytometric analysis showed that FOXP3 was expressed by the majority of CD4(+)CD25(high) T cells in peripheral blood. By contrast, less than half of the CD4(+)CD25(int) population were FOXP3(+), providing an explanation for observations in human T cells that regulatory activity is enriched within the CD4(+)CD25(high) pool. Although FOXP3 expression was primarily restricted to CD4(+)CD25(+) cells, it was induced following activation of both CD4(+) and CD8(+) T cell clones. These findings indicate that the frequency of FOXP3(+) cells correlates with the level of expression of CD25 in naturally arising regulatory T cells and that FOXP3 protein is expressed by some activated CD4(+) and CD8(+) T cell clones. These reagents represent valuable research tools to further investigate FOXP3 function and are applicable for routine clinical use.
Roncador
Giovanna
G
Monoclonal Antibodies Unit, Biotechnology Program, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid, Spain.
Brown
Philip J
PJ
Maestre
Lorena
L
Hue
Sophie
S
Martínez-Torrecuadrada
Jorge L
JL
Ling
Khoon-Lin
KL
Pratap
Sarah
S
Toms
Christy
C
Fox
Bridget C
BC
Cerundolo
Vincenzo
V
Powrie
Fiona
F
Banham
Alison H
AH
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D003429:Cross Reactions; D004268:DNA-Binding Proteins / Q000032:analysis* / Q000276:immunology; D051858:Forkhead Transcription Factors; D006801:Humans; D007108:Immune Tolerance; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D015375:Receptors, Interleukin-2 / Q000032:analysis*; D050378:T-Lymphocytes, Regulatory / Q000737:chemistry* / Q000502:physiology
D000911:Antibodies, Monoclonal; D004268:DNA-Binding Proteins; C418974:FOXP3 protein, human; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D015375:Receptors, Interleukin-2