Infection and Immunity, 2005, Vol. 73(7), p.3896
T-cell homing to infected skin is not well studied in humans. We examined sites experimentally infected with Haemophilus ducreyi by immunohistochemistry and flow cytometry for expression of receptors and ligands involved in cutaneous T-cell homing and determined the phenotypes of the T cells that trafficked to skin. Endothelial cells expressed E-selectin in infected but not uninfected skin, while peripheral node addressin (PNAd) was minimally expressed in all samples. CC chemokine ligand 27 (CCL27) was expressed in the epidermis and endothelium of both infected and uninfected skin. Interestingly, CCL21, a chemokine thought to be associated principally with T-cell trafficking in the lymphatic compartment, was highly expressed on the endothelium of infected skin. Few naive cells were present in experimental lesions, emphasizing the combined role of PNAd and CCL21 in trafficking of this subset. Memory cells (CD45RA super(-)) dominated both CD4 and CD8 T-cell populations at the site of infection. Effector memory (CD45RA super(-) CD27 super(-)) CD4 super(+) and CD8 super(+) T cells were enriched in lesions. Although the CC chemokine receptor 7-positive (CCR7 super(+)) population of both central memory (CD45RA super(-) CD27 super(+)) and effector memory cells was not enriched in the skin compared to peripheral blood, CCR7 super(+) cells were not precluded from entering infected skin. Taken together with our previous work (D. Soler, T. L. Humphreys, S. M. Spinola, and J. J. Campbell, Blood 101:1677-1683, 2003), these studies led us to propose a model of memory T-cell trafficking to skin in response to experimental H. ducreyi infection.
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