SPECTRAL EFFECTS IN ACTIVATION OF THE HUMAN-IMMUNODEFICIENCY-VIRUS PROMOTER BY PSORALENS PLUS ULTRAVIOLET-A TREATMENT

The effects of PUVA treatment on HIV promoter activation and cell kill ing in HIV cat/HeLa cells were studied using two UV sources, a UVASUN sunlamp and a WAR Photoactivation Chamber. A 4 to 5 times higher dose of ultraviolet radiation was required from the UVASUN lamp than from t he UVAR lamps: 1) to activate the HIV promoter in the presence of 0.1 or 1.0 mu g/ml 8-MOP and 2) to reduce cell survival to a level of 10%, in the presence of 0.1 or 1.0 mu g/ml 8-MOP. In addition, exposures p erformed with a fixed dose of 20 kJ/m(2) at varying concentrations of 8-MOP, required a 4.7 times higher combined PUVA dose from the UVASUN lamp than from the UVAR lamps. Two possible sources of these differenc es were analyzed: (1) the presence of UVB + UVA2 (280-340 nm) in the r adiation emitted by the UVAR, but not the UVASUN lamp, and its potenti al biological activity independent of 8-MOP, and (2) the difference in the overlap of the emission spectra of the two lamps with the absorpt ion spectrum of 8-MOP. The area of overlap was higher for the UVAR lam p than for the UVASUN lamp by a factor of 4.6, which is close to the d ifference between these two lamps in induction of the HIV promoter and killing HeLa cells. This indicates that the effectiveness of a partic ular UVA source used in combination with 8-MOP can be predicted by its congruence to the absorption spectrum of the photosensitizing drug.