The wavelength dependence of 8-methoxypsoralen photosensitization of host capacity inactivation in a mammalian cell-virus system

Inhibition of herpes virus plaquing capacity in human diploid fibroblasts treated with gilvocarcin V plus near UV radiation

The capacity of human fibroblasts to support plaque formation by Herpes simplex virus following treatment of the cells with gilvocarcin V, a polyaromatic C-glycoside, plus near ultraviolet radiation (UVA, 320-400 nm) was examined. Gilvocarcin V, plus UVA radiation, effectively inhibited host cell capacity at concentrations five orders of magnitude lower than that of 8-methyoxypsoralen required for capacity inhibition at similar levels of UVA radiation. This result extends the observation of unusual biological potency of UVA-activated gilvocarcins from bacterial cells to human cells.

Action spectra for 8-methoxypsoralen and 3-carbethoxypsoralen in skin fibroblasts in vitro

8-methoxypsoralen (8-MOP) and 3-Carbethoxypsoralen (3-CPs) are known photoreagents which have been employed in the treatment of psoriasis. Using skin fibroblasts grown in vitro we have determined the action spectra of both compounds in the long ultraviolet range. Narrow-band interference filters were applied to a Xenon lamp. Reduction in methyl-3H-thymidine (3H-TdR) uptake served as a parameter for photoinhibited cells. The results show a linear increate of 8-MOP-mediated photoinhibition with increasing wavelengths; 3-CPs showed comparatively weak inhibitory rates at the lower wavelength range (349-365 nm). Possibly this is due to the formation of 3-CPs photoproducts which are unreactive with DNA. Compared to 8-MOP, the monofunctional photoreagent 3-CPs is a weak photoinhibitor.

The wavelength dependence of 8-methoxypsoralen photosensitization of radiation-enchanced reactivation in a mammalian cell-virus system

The combined effect of 8-methoxypsoralen (8-MOP) and ultraviolet (UV) radiation on the ability of an irradiated mammalian cell (CV-1) to reactivate UV-irradiated mammalian virus (Herpes simplex) was tested. Prior treatment of cells with 8-MOP was found to increase Radiation-Enhanced Reactivation (RER) at one wavelength (297 nm) in the far ultraviolet but not at others (240-289 nm). This same treatment induced RER in the near UV (302-370 nm) and the visible region (380-400 nm). An action spectrum for the photo-sensitized induction of this cellular parameter was obtained. This action spectrum is consistent with the absorption spectrum for 8-MOP and the theory that damage to DNA is, at least in part, responsible for Radiation-Enhanced Reactivation.