The effect of cryo-treatment on epidermal Langerhans cells and immune function in mice

Different inflammatory mediators induce inflammation and pain after application of liquid nitrogen to the skin

The application of liquid nitrogen to the skin induces inflammation and pain. However, there is little data on the role of inflammatory mediators in the production of these symptoms. We have developed an experimental model to study some aspects of the inflammatory response and its mediators following the application of cold. We have applied liquid nitrogen jets to subcutaneous air pouches in the dorsal skin of rats to study the kinetics of the migration of inflammatory cells; also to the ear for histopathological analysis and on the paws for edema and pain. Inflammatory mediators were identified by pharmacological means. The results showed that the cellular inflammatory response was characterized by persistent cell migration, mainly of granulocytes. Histopathology of the ears confirmed these findings. Histamine and sympathomimetic mediators were mainly responsible for the resultant swelling. However, the hypernociception that resulted involved other mediators including IL-1 and eicosanoids. These data suggest that interference with the release of inflammatory mediators might reduce the side effects of cryosurgery and prevent hyperalgesia and inflammation at the site of application of cold.

Effects of near-infrared radiation on the epidermal proliferation and cutaneous immune function in mice

While ultraviolet radiation alters various cutaneous cell functions, little is known about the photobiological effects of infrared radiation (IR) on the skin except its local thermal effect. This study demonstrated that single exposure of mouse skin to near IR (0.7-1.3 microns) reversibly suppressed the proliferating activity of the epidermis, the density of Langerhans cells, and the ability of skin to induce contact hypersensitivity reaction. During the exposure, the ear surface temperature was elevated from a mean of 27 to 31.2 degrees C. The results suggest that near IR can modulate the epidermal proliferation and part of the skin immune system, with a mild thermal effect.

Induction of low zone tolerance to contact allergens in mice does not require functional Langerhans cells

Epidermal Langerhans cells are known to be the major controlling element in the development of contact hypersensitivity. Haptenic molecules permeating the skin are taken up locally by Langerhans cells and then presented to T lymphocytes in the regional lymph nodes. Despite the presence of functional Langerhans cells, however, subsensitizing doses of hapten applied epicutaneously induce tolerance. We examined epidermal Langerhans cells at the site of contact with picryl chloride or oxazolone in BALB/c and C57B1/6 mice with regard to their responding to either subsensitizing or sensitizing doses of allergen. Subsensitizing doses did not interfere with the membranous adenosine triphosphatase system on Langerhans cells, known to relate to functional readiness of the cell. Accordingly, on electron microscopy the ultrastructure of Langerhans cells was found to be like that in untreated skin. In contrast, sensitizing doses caused a significant depletion of adenosine triphosphatase-positive Langerhans cells, and electron microscopy revealed marked cellular activation of Langerhans cells, with enlarged nuclei and increased numbers of mitochondria and Birbeck granules. Furthermore, subsensitizing doses induced tolerance regardless of whether Langerhans cells were functionally intact or had their function blocked arbitrarily. Blocking was achieved either by preceding ultraviolet B irradiation at the site of application or by painting of a sensitizer before painting another sensitizer on the same site. Moreover, not even surgical removal of the site within minutes after painting could prevent the induction of tolerance. The data suggest that subsensitizing doses of contact allergens painted on normal murine skin bypass involvement of epidermal Langerhans cells.