Lethal Action of Ultraviolet and Visible (Blue‐violet) Radiations at Defined Wavelengths on Human Lymphoblastoid Cells: Action Spectra and Interaction Sites

Abstract

The repair proficient human lymphoblastoid line (TK6) has been employed to construcr an action spectrum for the lethal action of ultraviolet (UV) radiation in the range 254-434 nm and to examine possible interactions between longer (334, 365 and 405 nm) and shorter wavelength (254 and 313 nm) radiations. The action spectrum follows a DNA absorption spectrum fairly closely out to 360 nm. As in previously determined lethal action spectra for procaryotic and eucaryotic cell populations. there is a broad shoulder in the 334-405 nm region which could reflect the existence of either (a) a non-DNA chromophore or (b) a unique photochemical reaction in the DNA over this region. Pre-treatment with radiation at 334 or 365 nm causes either a slight sensitivity to (low fluences) or protection from (higher fluences) subsequent exposure to radiation at a shorter wavelength (254 or 313 nm). Pre-irradiation at a visible wavelength (405 nm) at all fluence levels employed sensitizes the populations to treatment with 254 or 313 nm radiations. These interactions will influence the lethal outcome of cellular exposure to broad-band radiation sources.

Heme oxygenase is the major 32-kDa stress protein induced in human skin fibroblasts by UVA radiation, hydrogen peroxide, and sodium arsenite.

“…UVA radiation was provided by a broadspectrum (330-450 nm) Uvasun 3000 lamp (Mutzhas, F.R.G.) and dose rates were monitored as described (12). Irradiation times were <15 min and control dishes were sham-irradiated.…”

Determination of the spectrum of mutations induced by defined-wavelength solar UVB (313-nm) radiation in mammalian cells by use of a shuttle vector.

“…Vector DNA at a concentration of 1 p.g/ml in Tris-buffered saline (pH 7.5) was irradiated at room temperature with either germicidal UVC (254-nm) radiation or monochromnatic UVB (313-nm) radiation. Details of light sources, filtration, and dosimetry have been described previously (25). CV-1 cells at about 50% confluence were transfected with pZ189 DNA (50 ng per 9-cm petri dish) by using the DEAE-dextran method (15).…”

Activation of flavin-containing oxidases underlies light-induced production of H 2 O 2 in mammalian cells

“…Previous studies have shown that irradiation of mammalian cells with violet or blue light induced H 2 O 2 production and DNA damage (1)(2)(3)(4)(5)(6)(7)(8)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25). Catalase and other antioxidants prevented this damage, indicating that H 2 O 2 production was a critical, early step in the process.…”

“…Less recognized or understood is that toxicity can be induced by visible light. Specifically, violet (400-450 nm) and blue (450-490 nm) light are known to cause mutations and even death of cultured mammalian cells at irradiation doses of 2-6 J/cm 2 (1)(2)(3)(4)(5)(6)(7)(8), which is equivalent to 5-10 min of direct sunlight (9). Although most human cells are protected from sunlight by physical barriers (skin, hair, clothing), clinical pathologies resulting from intense sources of violet-blue light have been reported, e.g., solar retinopathy (10,11) and erythropoietic protoporphyria (12,13).…”