Topical riboflavin attenuates ultraviolet B- and ultraviolet A-induced immunosuppression in humans.
BACKGROUND
Riboflavin (vitamin B(2)) plays a key role in cellular energy metabolism. We have observed previously that nicotinamide (vitamin B(3)), which is also centrally involved in cellular energy restoration after UV irradiation, is highly immune protective in humans. We thus hypothesized that riboflavin might also confer immune protection.


METHODS
We irradiated healthy, nickel-allergic volunteers with narrowband UVA (385 nm) and UVB (300 nm) at separate sites on the lower back. These areas were treated with riboflavin solution or vehicle at 24 h and again at 30 min before UV exposure. Forty-eight hours after irradiation, volunteers were patch tested with nickel-containing Finn chambers, at both irradiated and nonirradiated sites, with and without prior riboflavin treatment. The resulting contact hypersensitivity reactions at each site were then measured 72 h later with a reflectance erythema meter in order to determine and compare the immune suppressive effects of each intervention.


RESULTS
We observed that low doses of both UVB and longwave UVA1 were immune suppressive in humans. Topical riboflavin conferred immune protection against both wavebands.


CONCLUSIONS
Riboflavin is immune protective in humans, and this may reflect the role of the B group vitamins in cellular energy restoration after UV exposure.
Damian
Diona L
DL
Department of Dermatology, University of Sydney at Royal Prince Alfred Hospital, Camperdown, NSW, Australia. diona.damian@sswahs.nsw.gov.au
Matthews
Yasmin J
YJ
Halliday
Gary M
GM
D000287:Administration, Topical; D003877:Dermatitis, Contact / Q000188:drug therapy* / Q000209:etiology; D005260:Female; D006801:Humans; D007108:Immune Tolerance / Q000187:drug effects* / Q000528:radiation effects; D007155:Immunologic Factors / Q000008:administration & dosage*; D009532:Nickel / Q000009:adverse effects; D010328:Patch Tests; D017319:Photosensitizing Agents / Q000008:administration & dosage; D012256:Riboflavin / Q000008:administration & dosage*; D013997:Time Factors; D014466:Ultraviolet Rays / Q000009:adverse effects*
D007155:Immunologic Factors; D017319:Photosensitizing Agents; D009532:Nickel; D012256:Riboflavin