Analysis of FOXP3 protein expression in human CD4+CD25+ regulatory T cells at the single-cell level.

Journal article

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.

Authors: Roncador, G; Brown, P; Maestre, L; Hue, S; Martínez-Torrecuadrada, J

• Publication status: Published
• Journal: European journal of immunology
• Volume: 35
• Issue: 6
• Pages: 1681-1691
• Publication date: 2005-06-01
• DOI: 10.1002/eji.200526189
• EISSN: 1521-4141
• ISSN: 0014-2980
• Language: English
• Keywords: Cross Reactions; Humans; Animals; Receptors, Interleukin-2; DNA-Binding Proteins; Antibodies, Monoclonal; Mice, Inbred BALB C; Forkhead Transcription Factors; T-Lymphocytes, Regulatory; Lymphocyte Activation; Immune Tolerance; Mice