Phenotypical analysis of ectoenzymes CD39/CD73 and adenosine receptor 2A in CD4 + CD25 high Foxp3 + regulatory T-cells in psoriasis.

BACKGROUND: CD39 and CD73 are two novel cell surface markers of CD25high Foxp3+ regulatory T-cells (Tregs). Concordant expression of these two ectoenzymes not only discriminate Tregs from other cell populations, but also generates pericellular adenosine, which has been reported to suppress proliferation of activated T effector (Teff) cells. Because it is currently unclear whether human ectoenzymes (CD39/CD73) are involved in the impaired suppressive activity of Tregs in psoriasis, we examined the frequencies and phenotypes of CD39/CD73-expressing Tregs and related receptor adenosine receptor 2A (A2A R) in peripheral blood of patients with different types of psoriasis.

METHODS: Peripheral blood mononuclear cells (PMBC) were prepared from patients with three different types of psoriasis (psoriasis vulgaris, pustular psoriasis and erythrodermic psoriasis). CD4+ cells were separated from PBMC by negative selection on midiMACS columns, and the frequencies and phenotypes of CD39 and CD73 expressing Tregs, and A2A R expressing Teff were all determined by flow cytometry analysis. Blood from healthy volunteers served as controls.

RESULTS: The expression of single CD73+ Tregs was markedly reduced (approximately 50%) in psoriasis vulgaris, compared to normal controls. In pustular psoriasis, the mean numbers of CD39+ Tregs and A2A R+ Teff was significantly lower than in normal controls. Among three different types of psoriasis, CD39 expression was strikingly reduced in the blood Treg population of pustular psoriasis patients. Decreased CD73+ Tregs levels were observed in psoriasis vulgaris compared to pustular psoriasis and erythrodermic psoriasis.

CONCLUSIONS: The differences in the expression of CD39- and CD73- Tregs may be a factor in the pathogenesis of psoriasis.