RADIATION FROM ULTRAVIOLET PHOTOTHERAPY SOURCES RESULTS IN PHOTODEGRADATION OF 12(R) AND 12(S)-HYDROXY-EICOSATETRAENOIC ACID - HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AND POLYMORPH MIGRATION STUDIES

The effect of irradiation from Sylvania PUVA lamps (emitting predomina ntly in the ultraviolet (UVA) region) and broadband Philips TL-12 lamp s (peaking in the UVB region) on two inflammatory mediators, 12(R)- an d 12(S)-hydroxy-eicosatetraenoic acid (HETE) was studied. A high-perfo rmance liquid chromatography study showed significant photodegradation of both enantiomers at a concentration of 5 mug/ml in phosphate-buffe red saline following irradiation with 10 J. cm-2 UVA or 0.375 J . cm-2 UVB. The in vitro chemokinetic microdroplet migration response of hum an peripheral polymorphonuclear leukocytes from normal and psoriatic s ubjects was significantly reduced following irradiation of 12(R)-HETE at a concentration of 1 mug/ml in medium with 40 J . cm-2 UVA and 1.5 J. cm-2 UVB respectively. No such effect was seen with 12(S)-HETE. The effect of ultraviolet on skin physiology, and in particular in the su ccessful phototherapy of a range of inflammatory skin disorders, is no t fully understood. The photodegradation of inflammatory mediators suc h as 12-HETE, as shown in this study, provides another factor of possi ble therapeutic significance.