Alteration in murine epidermal Langerhans cell population by various UV irradiations: quantitative and morphologic

Type:Uv phototherapy Time:2017-12-20 14:15:50

Obata M, Tagami H.

Abstract

The present study was undertaken in order to clarify the exact mode of the Langerhans cell (LC) depleting process

caused by UV irradiation. Following irradiation with a single dose of various wavelengths of monochromatic UV

radiation (UVR), we studied the number of Ia-positive cells in mouse epidermal sheets quantitatively, particularly

with regard to dose-response relationship, action spectrum, and time course change. In addition, we studied

morphologic alterations of these cells using electron- and immunoelectron microscopy (EM and IEM). We obtained the

following results after a single dose of UVB radiation (200 mJ/cm2 of 300 nm) or PUVA (1% of 8-methoxypsoralen (8-

MOP) 20 microliter and 1 J/cm2 of 360 nm): (1) EM and IEM showed that while some LCs simply lost their Ia marker

without any structural alterations, the majority of the LCs disappeared due to actual cell damage. (2) During an

"injury phase," the initial 48 h, and a "recovery phase," lasting from 4-14 days after irradiation,

enlargement of

the size of remaining Ia-positive LCs occurred. The degree of enlargement was closely related to the degree of

reduction in number, suggesting a process compensating for the loss of the LC population. (3) It was found that the

recovery rate of LCs after irradiation damage was slower than that of keratinocytes, indicating different cell

kinetics between these distinct cell populations in the epidermis, i.e., restoration of LCs after irradiation seems

to be achieved at least partially through a repopulation process originating in the bone marrow. Studies with

irradiation of various monochromatic wavebands, with or without topical 8-MOP, showed that the action spectrum for

Ia-positive cell depletion activity lay within the spectrum shorter than 300 nm for UVR alone, and between 320-380

nm for 8-MOP plus UVR. Since the action spectra were similar to those for keratinocyte damage, i.e., sunburn cell

formation, induction of unscheduled DNA synthesis, and to those for UVR-induced erythema, we conclude that common

mechanisms underlie these types of tissue damage.

www.kerneluvb.com----The leader manufacturer of UVB Phototherapy.