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Conjunctival FOXP3 in Trachoma: T Cells Not Specified

The article by Faal et al. [1] describes differences in the level of FOXP3 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 FOXP3 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 FOXP3 mRNA should be considered with great caution. According to the current state-of-the-art it is well established that FOXP3 does not specify human regulatory T cells since it is expressed at the mRNA and the protein levels to different extents protein at [25]. 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.


  1. 1. Faal N, Bailey RL, Jeffries D, Joof H, Sarr I, et al. (2006) Conjunctival FOXP3 expression in trachoma: Do regulatory T cells have a role in human ocular Chlamydia trachomatis infection? PLoS Med 3: e266.
  2. 2. Ziegler SF (2006) FOXP3: Of mice and men. Annu Rev Immunol 24: 209–226.
  3. 3. Gavin MA, Torgerson TR, Houston E, DeRoos P, Ho WY, et al. (2006) 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 103: 6659–6664.
  4. 4. Ocklenburg F, Moharregh-Khiabani D, Geffers R, Janke V, Pfoertner S, et al. (2006) UBD, a downstream element of FOXP3, allows the identification of LGALS3, a new marker of human regulatory T cells. Lab Invest 86: 724–737.
  5. 5. Mantel PY, Ouaked N, Ruckert B, Karagiannidis C, Welz R, et al. (2006) Molecular mechanisms underlying FOXP3 induction in human T cells. J Immunol 176: 3593–3602.
  6. 6. Seddiki N, Santner-Nanan B, Martinson J, Zaunders J, Sasson S, et al. (2006) Expression of interleukin (IL)-2 and IL-7 receptors discriminates between human regulatory and activated T cells. J Exp Med 203: 1693–1700.
  7. 7. Liu W, Putnam AL, Xu-Yu Z, Szot GL, Lee MR, et al. (2006) CD127 expression inversely correlates with FoxP3 and suppressive function of human CD4+ T reg cells. J Exp Med 203: 1701–1711.