Alteration of lipoproteins of suction blister fluid by UV radiation.

Suction blister fluid is a good representative of the interstitial fluid feeding the epidermal cells. Lipoproteins contained in the suction blister fluid of healthy volunteers are readily photo-oxidized by UV radiation in the wavelength range 290-385 nm. Absorbed light doses equivalent to one minimal erythemal dose absorbed by skin exposed to UVB (e.g. 290-320 nm) are sufficient to induce lipid peroxidation and modification of apolipoproteins A-I, A-II and B. Albumin, which is known to protect serum fully from oxidative stresses, is not so effective against photo-oxidation. Although tryptophan (Trp) residues of proteins contained in the suction blister fluid are photo-oxidized, apolipoprotein A-II, which does not contain any chromophoric Trp residue, is also altered by the UV radiation. With regard to results obtained with a model reconstituted fluid, it is suggested that the radical chain reaction of the lipid peroxidation can transfer the initial photodamage at sites not directly susceptible to photo-oxidation. The biological implications of these results are discussed.