Effect of ultraviolet B on nonimmunologic contact reactions induced by dimethyl sulphoxide, phenol and sodium lauryl sulphate.

The effect of ultraviolet light B (UVB) on immediate and delayed irritant reactions induced by dimethyl sulphoxide (DMSO), phenol, and sodium lauryl sulphate (SLS) was studied in 12 volunteers. One half of the upper back was irradiated with 0.16 J/cm2 of UVB. Patch tests for immediate reactions were performed using dilution series of test substances on the 3rd, 9th and 15th days and for delayed reactions on the 2nd, 8th and 14th days after irradiation both on the UV-exposed and non-exposed areas of the back. The occlusion time was 20 min for immediate reactions and 20 h for delayed ones. Changes in the skin blood flow of the test sites were monitored using laser-Doppler flowmetry, and erythema and edema reactions were observed visually. Both immediate and delayed reactions were caused by DMSO and phenol; SLS elicited only delayed reactions. UVB diminished immediate reactions induced by phenol for at least 15 days after irradiation. Immediate reactions to DMSO were diminished 40 min after application on the UV-exposed area on the 3rd day. UVB diminished the delayed reactions from SLS and DMSO but not reactions induced by phenol.