The article by Faal et al. [1] describes differences in the level of FOXP 3 mRNA expression in the conjunctiva of patients with Chlamydia trachomatis infection. The authors suggest that their results may indicate a role for regulatory T cells in the resolution of conjunctival immune response, since FOXP 3 mRNA remained elevated even if clinical disease signs were present in the absence of infection.
But suggestions about the function of regulatory T cells in diseases based only on the quantification of FOXP 3 mRNA should be considered with great caution. According to the current state-of-the-art it is well established that FOXP 3 does not specify human regulatory T cells since it is expressed at the mRNA and the protein levels to different extents protein at [2–5]. Thus, without quantification of FOXP3 the single cell level in conjunction with reliable markers of human regulatory T cells, e.g., the recently identified lack of CD127 expression on regulatory T cells [6,7], the potential contribution or association of regulatory T cells with a disease cannot be assessed.
Footnotes
Funding: The author received no specific funding for this article.
Competing Interests: The author has declared that no competing interests exist.
References:
- Faal N, Bailey RL, Jeffries D, Joof H, Sarr I, et al. Conjunctival FOXP3 expression in trachoma: Do regulatory T cells have a role in human ocular Chlamydia trachomatis infection? PLoS Med. 2006;3:e266. doi: 10.1371/journal.pmed.0030266. doi: 10.1371/journal.pmed.0030266. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ziegler SF. FOXP3: Of mice and men. Annu Rev Immunol. 2006;24:209–226. doi: 10.1146/annurev.immunol.24.021605.090547. [DOI] [PubMed] [Google Scholar]
- Gavin MA, Torgerson TR, Houston E, DeRoos P, Ho WY, et al. Single-cell analysis of normal and FOXP3-mutant human T cells: FOXP3 expression without regulatory T cell development. Proc Natl Acad Sci U S A. 2006;103:6659–6664. doi: 10.1073/pnas.0509484103. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ocklenburg F, Moharregh-Khiabani D, Geffers R, Janke V, Pfoertner S, et al. UBD, a downstream element of FOXP3, allows the identification of LGALS3, a new marker of human regulatory T cells. Lab Invest. 2006;86:724–737. doi: 10.1038/labinvest.3700432. [DOI] [PubMed] [Google Scholar]
- Mantel PY, Ouaked N, Ruckert B, Karagiannidis C, Welz R, et al. Molecular mechanisms underlying FOXP3 induction in human T cells. J Immunol. 2006;176:3593–3602. doi: 10.4049/jimmunol.176.6.3593. [DOI] [PubMed] [Google Scholar]
- Seddiki N, Santner-Nanan B, Martinson J, Zaunders J, Sasson S, et al. Expression of interleukin (IL)-2 and IL-7 receptors discriminates between human regulatory and activated T cells. J Exp Med. 2006;203:1693–1700. doi: 10.1084/jem.20060468. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Liu W, Putnam AL, Xu-Yu Z, Szot GL, Lee MR, et al. CD127 expression inversely correlates with FoxP3 and suppressive function of human CD4+ T reg cells. J Exp Med. 2006;203:1701–1711. doi: 10.1084/jem.20060772. [DOI] [PMC free article] [PubMed] [Google Scholar]