The number and distribution of blood dendritic cells in the epidermis and dermis of healthy human subjects.

Human blood dendritic cells (BDC) can be divided into three subsets: plasmacytoid DC (PDC) and two myeloid subsets--MDC1 and MDC2. Several studies revealed the presence of both MDC and PDC in blood of healthy subjects, however no precise literature data exist on the number and distribution of BDC in the skin. The aim of our study was to assess the number and distribution of BDC and their subtypes in the healthy skin. The-study included 30 healthy volunteers (age 18-51). Punch biopsies were taken from the buttock skin from each subject, and immunofluorescent staining was performed using monoclonal mouse IgG1 antibodies directed against BDCA-1, BDCA-2, BDCA-3 and BDC-4. The BDC were present both in the epidermis and dermis. PDC were detected mainly in the dermis (mean 1.2 cells per field). Myeloid subtypes were observed mainly in the middle layers of the epidermis and in the upper part of the dermis (mean 1.8 cells per field). The detection of blood dendritic cells in the skin proves their role in immune cutaneous surveillance.