Abstract
The epidermis is composed of keratinocytes that bind tightly each other. This feature contrasts to the property of the dermis where cellular density is low and filled with extracellular matrix. Therefore, it remains a question how Langerhans cells, a subtype of dendritic cells in the epidermis, migrate within such a “packed” area. Here, we examined the motility of Langerhans cells in the contact hypersensitivity response by means of two-photon microscopy. First, we labeled cellular membrane of keratinocytes with a fluorescent lectin, and revealed that there exist 1-2 nm gaps between adjacent keratinocytes in vivo. In the steady state, and even in the first encounter of hapten (sensitization phase), almost all of Langerin + cells were static and elongated their long dendrites upward through the gaps. In the second encounter of hapten (elicitation phase), however, a subpopulation of Langerin + dendritic cells move downward to the basal layer of epidermis and actively interact with T cells, whereas another population of Langerin + dendritic cells were anchored with upstretched dendrites. Intriguingly, a depletion of Langerin + dendritic cells in elicitation phase resulted in prolonged skin inflammation.Our study has demonstrated that the gaps between keratinocytes provide a migratory pathway for immune cells. It should be essential for the immune cells in the epidermis to migrate in a non-tissue destructive manner. Moreover, we showed that epidermal Langerin + cells are divided into two populations according to their kinetics and morphology, and both or either of them may have a role in termination of inflammation in the elicitation phase of contact hypersensitivity. JSID AbstractsJournal of Dermatological ScienceVol. 69Issue 2Preview Full-Text PDF
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