Effect of selective ultraviolet phototherapy on DNA and antinuclear antibody titers in psoriatic patients.

The sera of 21 psoriatics treated by selective ultraviolet phototherapy (SUP) for 1-7 months were screened for IgG- and IgM-anti-DNA antibodies and antinuclear antibodies (ANAs) by standardized ELISA and the indirect immunofluorescence technique. No patients developed IgG-antibodies against native DNA under SUP, but two patients increased their IgM-antibody titers five- and tenfold, respectively. The IgG- and IgM-anti-single-stranded-(ss)DNA antibody titers remained unaltered in 38% and 57% of the patients. In 43% and 24%, respectively, they rose to a maximum of three times their original; and in 20% they decreased to a minimum of 40% of their pretherapeutic titers. After 1 month therapy no patient had produced ANAs, but all three patients showing ANAs before therapy had increased titers (one titer step). These remained on the elevated level or were even further increased by one-titer step during progressive therapy. Two patients out of 14 developed low titers of IgM-(1:20) or IgA-(1:40)ANAs against deoxyribonucleoprotein (DNP), initially after 3 months of irradiation; in one of them IgG-ANAs (titer 1:10) against DNP were additionally formed after 6 months of therapy. Our results suggest that lesions in DNA and DNP generated by SUP trigger an immune response to nuclear antigens.