Studies on the repopulation of Langerhans cells in partial-thickness wounds. Air exposed and occlusively dressed

The use of occlusive dressings on partial-thickness wounds has been shown to promote early epithelization and connective tissue regeneration. Because Langerhans cells (LC) have been implicated in epidermal homeostasis we studied the rate of repopulation of LC in air-exposed vs occlusively dressed wounds. Partial-thickness wounds on the backs of pigs were treated with occlusive dressings (Tegaderm) for 3 days or left air exposed. On days 3, 5, 7, and 11 after keratome wounding, epidermal sheets from the regenerating wounds were isolated and stained for LC using indirect immunofluorescence. The LC populations were quantified in the interfollicular regions and expressed as average number of cells per square millimeter of epidermis.

Normal skin control had 1024 +/- 93 LC/mm2 distributed uniformly. On day 3 after wounding occlusive-dressing-treated wounds had an LC repopulation of 46% of the original value. Langerhans cells in air-exposed skin could not be evaluated until epithelization occurred at day 5. Langerhans cells in both air-exposed and occlusive-dressing-treated wounds were 46% to 51%, 65% to 71%, and 91% of normal value, respectively, on days 5, 7, and 11.

We conclude that at least in regenerating epidermis, the degree of repair of the new epidermis apparently plays a limited role in the migration of LC, as does the earlier growth of blood vessels.