Studies of the action spectrum for induction of photosensitivity to tetrachlorosalicylanilide in mice.

We have developed a new system, using ear swelling in mice, to study the action spectrum for the induction of photosensitivity to tetrachlorosalicylanilide (TCSA). Using narrow-band interference filters, we produced data for action spectra between 250 nm and 421 nm with doses of 0.5 J/cm2 and 0.2 J/cm2. We found that the higher dose generally produced greater reactions. The action spectrum was similar to the absorption spectrum for TCSA in the UVA region. The reduced responses in the UVB and UVC regions may be due to immunological suppression produced by these parts of the spectrum.