Photosensitivity in lupus erythematosus (LE) was studied by action spectra production of persistent erythema or LE-like lesions with monochromatic radiation (4-nm band width) at test sites. Skin biopsy specimens were examined for development of immunoglobulins.
Action spectra for fixed discoid lupus erythematosus (DLE) (six cases) were similar to controls (tested range, 250 to 313 nm). In disseminated DLE, clinically more photosensitive, the minimal erythemal dosages (MEDs) were lower than the mean although they were within the standard deviation of controls; erythema could be produced up to 330 nm in three cases; LE-like lesions produced with 8 to 13 MEDs of monochromatic radiation of 250 to 313 nm at radiation test sites lasted more than ten weeks. Immunofluorescence at test sites was not detected before seven weeks.
Cripps DJ, Rankin J. Action Spectra of Lupus Erythematosus and Experimental Immunofluorescence. Arch Dermatol. 1973;107(4):563-567. doi:10.1001/archderm.1973.01620190039009