STUDIES ON THE REPOPULATION OF LANGERHANS CELLS IN PARTIAL-THICKNESS WOUNDS - AIR EXPOSED AND OCCLUSIVELY DRESSED

Background and Design.-The use of occlusive dressings on partial-thick ness wounds has been shown to promote early epithelization and connect ive tissue regeneration. Because Langerhans cells (LC) have been impli cated in epidermal homeostasis we studied the rate of repopulation of LC in air-exposed vs occlusively dressed wounds. Partial-thickness wou nds on the backs of pigs were treated with occlusive dressings (Tegade rm) for 3 days or left air exposed. On days 3,5,7, and 11 after kerato me wounding, epidermal sheets from the regenerating wounds were isolat ed and stained for LC using indirect immunofluorescence. The LC popula tions were quantified in the interfollicular regions and expressed as average number of cells per square millimeter of epidermis. Results.-N ormal skin control had 1024+/-93 LC/mm2 distributed uniformly. On day 3 after wounding occlusive-dressing-treated wounds had an LC repopulat ion of 46% of the original value. Langerhans cells in air-exposed skin could not be evaluated until epithelization occurred at day 5. Langer hans cells in both air-exposed and occlusive-dressing-treated wounds w ere 46% to 51%,65% to 71%, and 91% of normal value, respectively, on d ays 5, 7, and 11. Conclusions.-We conclude that at least in regenerati ng epidermis, the degree of repair of the new epidermis apparently pla ys a limited role in the migration of LC, as does the earlier growth o f blood vessels.