Citation: Probst-Kepper M (2006) Conjunctival FOXP3 in Trachoma: T Cells Not Specified. PLoS Med 3(11): e506. doi:10.1371/journal.pmed.0030506
Published: November 28, 2006
Copyright: © 2006 Michael Probst-Kepper. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: The author received no specific funding for this article.
Competing interests: The author has declared that no competing interests exist.
The article by Faal et al.  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 [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.
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