PROLONGED INCREASE OF CIS-UROCANIC ACID LEVELS IN HUMAN SKIN AND URINE AFTER SINGLE TOTAL-BODY ULTRAVIOLET EXPOSURES

Cis-urocanic acid (cis-UCA), a mediator of immunosuppression, is forme d from trans-UCA upon UV-exposure of the skin, This study describes a liquid chromatographic method for the simultaneous quantification of c is- and trans-UCA in skin, urine and plasma of nonirradiated volunteer s, It also describes cis- and trans-UCA kinetics in UV-irradiated volu nteers, New procedures to remove interfering substances from urine and plasma are reported, Normal levels of cis-UCA in skin, urine and plas ma of nonirradiated volunteers were 0.5 nmol/cm(2), 0.03 mu mol/mmol c reatinine (median 0.00) and undetectable and those of trans-UCA were 1 7.1 nmol/cm(2), 1.36 mu mol/ mmol creatinine and 0.5 mu M, respectivel y, Upon single total body UVB (290-320 nm) exposures of 250 J/m(2), ep idermal cis-UCA levels immediately reached a maximum and returned to b asic levels 3 weeks later, The cis-UCA levels in urine reached a maxim um in 5-12 h postirradiation and reached baseline values in 8-12 days. Additionally, a single total body UVA (320-400 nm) irradiation of 200 kJ/m(2) yielded a similar pattern, The kinetics of cis-UCA in plasma could not be followed due to low concentrations; however, that of skin and urine was informative in relation to solar exposures and photothe rapy.