Contrasting effects of an ultraviolet B and an ultraviolet A tanning lamp on interleukin-6, tumour necrosis factor-alpha and intercellular adhesion molecule-1 expression.
BACKGROUND
Recent studies have demonstrated that a tanning lamp emitting predominantly ultraviolet (UV) A induces significant yields of the type of potentially mutagenic DNA damage that are associated with the onset of skin cancer (i.e. cyclobutane pyrimidine dimers). UV-induced immunosuppression is also an important event leading to skin cancer.


OBJECTIVE
To the modulation of key immunological molecules following exposure to a broad-spectrum UVB lamp and a predominantly UVA-emitting tanning lamp using model in vitro systems.


METHODS
We compared secretion and mRNA expression of interleukin (IL)-6 and tumour necrosis factor (TNF)-alpha in normal human epidermal keratinocytes, and interferon (IFN)-gamma-induced intracellular adhesion molecule (ICAM)-1 in normal human fibroblasts irradiated in vitro with a broad-spectrum UVB lamp or with a Philips 'Performance' tanning lamp.


RESULTS
With broad-spectrum UVB irradiation, upregulation of IL-6 and TNF-alpha mRNA was detected 6 h after irradiation, and a dose-dependent increase of cytokines in the supernatants of irradiated cells was found 24 h after irradiation. In contrast, there was no cytokine secretion and little evidence for mRNA upregulation following exposure to a tanning lamp. When cells were exposed first to broad-spectrum UVB, then the tanning lamp, UVB-induced cytokine secretion was inhibited, although mRNA levels were upregulated to a level close to that observed with UVB alone. By using a Schott WG 320 nm filter to attenuate the level of UVB relative to UVA emitted by the tanning lamp, the inhibition of cytokine secretion was shown to be associated with UVA exposure. Both UV sources inhibited IFN-gamma-induced ICAM-1 mRNA expression in a dose-dependent fashion. By using a Schott WG 335 nm filter, inhibition of ICAM-1 mRNA expression by the tanning lamp was shown to be associated with UVB exposure.


CONCLUSIONS
These results suggest that UV sources emitting different levels of UVA and UVB have differential effects on the modulation of different immunoregulatory molecules, and indicate that there are potential interactions between these wavelengths.
Clingen
P H
PH
CRC Drug--DNA Interaction Research Group, Department of Oncology, University College London Medical School, 91 Riding House Street, London W1P 8BT, UK. P.Clingen@ucl.ac.uk
Berneburg
M
M
Petit-Frère
C
C
Woollons
A
A
Lowe
J E
JE
Arlett
C F
CF
Green
M H
MH
D001505:Beauty Culture; D018929:Cell Culture Techniques; D004307:Dose-Response Relationship, Radiation; D005347:Fibroblasts / Q000378:metabolism / Q000528:radiation effects; D006801:Humans; D007108:Immune Tolerance / Q000528:radiation effects; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D015603:Keratinocytes / Q000276:immunology / Q000528:radiation effects; D011740:Pyrimidine Dimers / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012867:Skin / Q000276:immunology / Q000528:radiation effects*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D014466:Ultraviolet Rays; D015854:Up-Regulation / Q000528:radiation effects
D015850:Interleukin-6; D011740:Pyrimidine Dimers; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1