ALTERATION OF LIPOPROTEINS OF SUCTION BLISTER FLUID BY UV-RADIATION

Suction blister fluid is a good representative of the interstitial flu id feeding the epidermal cells. Lipoproteins contained in the suction blister fluid of healthy volunteers are readily photo-oxidized by UV r adiation in the wavelength range 290-385 nm. Absorbed light doses equi valent to one minimal erythemal dose absorbed by skin exposed to UVB ( e.g. 290-320 nm) are sufficient to induce lipid peroxidation and modif ication of apolipoproteins A-I, A-II and B. Albumin, which is known to protect serum fully from oxidative stresses, is not so effective agai nst photooxidation. Although tryptophan (Trp) residues of proteins con tained in the suction blister fluid are photo-oxidized, apolipoprotein A-II, which does not contain any chromophoric Trp residue, is also al tered by the UV radiation. With regard to results obtained with a mode l reconstituted fluid, it is suggested that the radical chain reaction of the lipid peroxidation can transfer the initial photodamage at sit es not directly susceptible to photo-oxidation. The biological implica tions of these results are discussed.