A study of the photodegradation of leukotriene B4 by ultraviolet irradiation (UVB, UVA).
In view of the presence of the polymorphonuclear leukocyte (PMN) chemoattractant Leukotriene B4 (LTB4) in the surface scale of the psoriatic lesion and the known therapeutic effect of phototherapy in psoriasis, the photostability of LTB4 was investigated. LTB4 was irradiated with dosages of UVB (290-320 nm) ranging from 100-1500 mJ cm-2 and with dosages of UVA (320-400 nm) ranging from 5-40 J cm-2. Topical application of UVB irradiated LTB4 to the forearm skin of normal volunteers showed a marked reduction in cutaneous erythema, paralleled histologically by reduced transepidermal PMN migration when compared with sites of application of unirradiated and UVA irradiated LTB4. High performance liquid chromatography (HPLC) demonstrated a dose-dependent photodegradation of LTB4 by UVB irradiation. UVA irradiation produced no such effect. The wavelengths responsible lie within the absorption spectrum of LTB4. In vitro chemotaxis studies, using an under agarose technique, showed a statistically significant reduction in the migration of PMN from both psoriatic and non-psoriatic subjects to the UVB irradiated LTB4 compared with the unirradiated LTB4, whilst UVA irradiated LTB4 produced a normal PMN chemotactic response.
Millar
B
B
Department of Pharmacy, Ninewells Hospital, Dundee, U.K.
Green
C
C
Ferguson
J
J
Raffle
E J
EJ
Macleod
T M
TM
D002634:Chemotaxis, Leukocyte; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007975:Leukotriene B4 / Q000378:metabolism / Q000528:radiation effects*; D009504:Neutrophils; D010777:Photochemistry; D011565:Psoriasis / Q000378:metabolism; D014466:Ultraviolet Rays
D007975:Leukotriene B4