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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
PubMed

Insights

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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