Optimization of tetrachlorosalicylanilide and ultraviolet A doses at sensitization and challenge for contact photosensitivity in the mouse.

We studied contact photosensitivity (CPS) to tetrachlorosalicylanilide (TCSA) in BALB/cJ mice with various doses of TCSA and UVA at sensitization and challenge. From these studies we recommend the following protocol: sensitization on days 0 and 1 with 50 microliters of 1% TCSA followed by 3 J/cm2 of UVA, and challenge on day 7 with 10 microliters of 3% TCSA followed by 6 J/cm2 of UVA. This gave an ear swelling response of 27.4 +/- 0.6 x 10(-3) (mean +/- standard error). We also demonstrated that there is reciprocity between volume and concentration of TCSA at sensitization but not between TCSA and UVA doses at sensitization.