Up-regulated expression of CD86 on circulating intermediate monocytes correlated with disease severity in psoriasis.

BACKGROUND: The number of intermediate monocytes (CD14++CD16+) increases in many inflammatory conditions. However, it is not yet known which functional markers expressed by these populations are linked to the pathogenesis of psoriasis. OBJECTIVES: We evaluated the expression of functional markers on circulating intermediate monocytes. Our goal was to correlate specific populations and their markers with the clinical severity of psoriasis. METHODS: A cohort of 43 psoriatic patients was subjected to analysis. The proportion of intermediate monocytes with CD86 expression was evaluated by flow cytometry. Serum beta defensin-2 levels were measured by ELISA. Immunofluorescent staining was performed in order to identify the presence of CD14+CD16+ cells that co-expressed CD86 in affected skin tissues. RESULTS: Upregulated expression of CD86 on the intermediate subset (but not the number of intermediate monocytes) correlated with clinical severity as measured by PASI scores and serum beta defensin-2 levels. Immunostaining also showed the presence of CD86+CD14+CD16+ cells in the epidermis and dermis of psoriatic plaques, which was associated with increased epidermal proliferation. CONCLUSION: These results suggest that the expression of CD86 on circulating intermediate monocytes could be used as an index in clinical practice and provide novel insights into how these cells join a complex immune network under the pathological conditions of psoriasis.