Mastociti e cellule dendritiche della cute e delle mucose analisi morfologiche e funzionali in condizioni normali e sperimentali

Studies on Langerhans cells Langerhans cells are considered as the major responsible for the sensitization against antigens in the epidermis. Ultraviolet B radiation (UVB) is known to inhibit the sensitization against haptens applied to the skin surface and this effect is mediated by cis-urocanic acid and TNFα , which in turn alter the immune function of Langerhans cells and perhaps also of other antigen presenting cells of the skin. Since the shape of Langerhans cells changes upon UVB, the hypothesis has been proposed that the deleterious effect of this radiation on Langerhans cells depends on an alteration of the cytoskeleton of these cells. To address this issue, the number and shape of Langerhans cells and the expression of vimentin (the protein constituent of the intermediate filaments) by these same cells have been evaluated in the mouse skin upon treatment with UVB and with chemical agents mediating UVB effect, namely cis-urocanic acid and TNFα . The results have shown that all these agents lead to a reduction in number and loss of dendrites of Langerhans cells and to a partial inhibition of the expression of vimentin by these same cells. To test whether damage to the cytoskeleton can be directly responsible for an altered immune function of Langerhans cells, the mouse skin was treated with vinblastine, followed by a hapten, and the onset of contact hypersensitivity against the hapten was monitored. Vinblastine directly damages microtubules, however it affects indirectly also the intermediate filament network, since this is connected with microtubules. This happens also in Langerhans cells, since in this study it was demonstrated that Langerhans cells are affected by vinblastine in a similar way as by UVB: they