Psoralen photobiology and photochemotherapy: 50 years of science and medicine

In 1998 it is appropriate to commemorate the 50th anniversary of el Mofty's use of purified 8-methoxypsoralen (8-MOP) in the treatment of vitiligo (el Mofty AM. A preliminary clinical report on the treatment of leukoderma wit h Ammi majus linn. J R Egypt Med Assn 1948,31:651-65. el Mofty AM, el Sawal hy H, el Mofty M. Clinical study of a new preparation of 8-methoxypsoralen in photochemotherapy. Int J Dermatol 1994,8.588-92). Two young American der matologists (Aaron Lerner and Thomas Fitzpatrick) were intrigued by the pot ency of this material. After Lerner determined that artificial long wavelen gth ultraviolet (320-400 nm, UVA) radiation was the most efficient for acti vating 8-MOP: the development of artificial sources enabled the efficient d elivery of these photons to skin containing 8-MOP. Their initial studies fo r vitiligo led to further development of this therapy for the treatment of psoriasis (Parrish JA, Fitzpatrick TB, Tannenbaum L, et al. Photochemothera py of psoriasis with oral methoxsalen and long-wave ultraviolet light. New Engl J Med 1974,291:1207-11. Honigsmann H, Fitzpatrick TBI Pathak MA, et al . Oral photochemotherapy with psoralen and WA (PUVA): principles and practi ce. In: Fitzpatrick TB, Eisen AZ, Wolf K, editors. Dermatology in General M edicine. New York: McGraw-Hill. 1987:1728-54). This photochemotherapy came to be called 'PUVA' (psoralen + UVA). The position PUVA holds today as one of the most common procedures performed in dermatology can be traced to the ir initial curiosity and their subsequent ingenuity. Further developments i n more recent years capitalized on their seminal work. The therapy met with unprecedented success from the outset, leaving little perceived need to un derstand underlying science. However, in recent years there has been a new found interest in the basic aspects of psoralen photobiology and molecular mechanistic events contributing to therapeutic responses as well as to the development of skin cancers in PUVA patients. These will be surveyed in thi s review commemorating the 50 years of modern psoralen photobiology and pho tomedicine. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.