Long term effect on epidermal dendritic cells of four different types of exogenous inflammation.

In the present study we produced allergic, irritant, ultraviolet and liquid nitrogen inflammation in human volunteers. Biopsies were taken from each test site and adjacent normal skin as control 4-5 weeks later. The monoclonal antibodies OKT 6 and HLA-DR were used for light microscopic detection of Langerhans' cells (LC). At all 4 post-inflammatory test sites the number of epidermal LC (OKT 6 positive as well as HLA-DR positive) were significantly increased compared to normal skin. Also, the density of dermal dendritic cells was increased in post-inflammatory test sites. The increased number of epidermal LC seems to be a result of inflammation and not a specific event strongly related to certain cutaneous inflammatory disorders. The present investigation supports the theory that epidermal LC play a role in skin homeostasis.