THE PROLIFERATIVE AND TOXIC EFFECTS OF ULTRAVIOLET-LIGHT AND INFLAMMATION ON EPIDERMAL PIGMENT-CELLS

[摘要] The mouse ear is useful for studying the effects of UV light on epidermal pigment cells. The quantity of light penetrating the skin causing an inflammatory response can be assessed easily by measuring the swelling with an engineering calipers. The inflammatory response exhibits a linear relationship to the dose of light delivered. Doses of shortwave UV light which are noninflammatory when repeated at daily intervals induce moderate to severe inflammation. Small doses of psoralen and prolonged exposure to UVA (PUVA) were more inflammatory than larger amounts of psoralen and short exposure to light. Doses of shortwave UV light and PUVA which produce only a minimal inflammation of the skin stimulate the proliferation of epidermal melanocytes. PUVA in doses sufficiently large to cause a marked inflammatory reaction in the skin seems injurious to pigment cells and kills them or causes only a minimal proliferative response. The inflammatory reaction itself does not seem to stimulate or inhibit the proliferation of melanocytes. Prostaglandins A, E and F2.alpha. have no effect on the proliferation of epidermal pigment cells. Dimethyl sulfoxide (DMSO) and allergic contact dermatitis increase the numerical density of pigment cells. Steroids may block the function of the enzyme tyrosinase. Experiments indicate that pigment cells, like many other varieties of cells, are susceptible to injury and can be killed at least by large doses of PUVA.