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Ultraviolet a radiation suppresses an established immune response: implications for sunscreen design
D X Nghiem1, N Kazimi, G Clydesdale
1The Department of Immunology, The University of Texas, MD Anderson Cancer Center, The Graduate School of Biomedical Sciences, Houston, Texas 77030, USA.
The Journal of Investigative Dermatology
|November 17, 2001
Summary
Sunlight
Area of Science:
- Immunology
- Dermatology
- Photobiology
Background:
- Ultraviolet (UV) radiation in sunlight is a primary cause of nonmelanoma skin cancer and contributes to malignant melanoma.
- UV radiation has immunosuppressive properties, increasing skin cancer risk and impairing immune responses to infections.
- While UV's effect on naive immune systems is known, its impact on established immune reactions is less understood.
Purpose of the Study:
- To investigate the effect of solar-simulated UV radiation, applied post-immunization, on established immune responses.
- To identify specific UV wavelengths responsible for immune suppression.
- To assess the efficacy of UV filters in sunscreens against UV-induced immune suppression.
Main Methods:
- Mice were immunized, then exposed to solar-simulated UV radiation.
- Delayed-type hypersensitivity (DTH) reactions were measured to assess immune suppression.
- Specific UV wavelengths (UVA, UVB, UVA+B) and sunscreen filters were used to pinpoint causative agents and protective measures.
Main Results:
- UV radiation applied after immunization suppressed immunologic memory and DTH reactions.
- Ultraviolet A (UVA) wavelengths (320-400 nm) were critical for this immune suppression.
- Sunscreens with UVA+B filters blocked UV-induced immune suppression, while UVB-only filters did not.
Conclusions:
- Solar UV radiation, particularly UVA, can suppress established immune responses and immunologic memory.
- This immunosuppression may reduce the effectiveness of prior vaccinations and protection against infections.
- Sun protection strategies should include UVA filters to prevent UV-induced immune suppression.
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