UVB-induced immune suppression and infection with Schistosoma mansoni.
Irradiation with ultraviolet B (UVB, 290-320 nm) causes a systemic immunosuppression of cell-mediated immunity. The question of whether UV immunosuppression modulates the course of infectious diseases is important because UVB levels in sunlight are sufficient to predict significant UV-induced immunosuppression at most latitudes. We have investigated the effect of immunosuppressive doses of UVB on the disease caused by the helminth parasite Schistosoma mansoni. C57BL/6 mice were irradiated once or three times weekly over 60-80 days with UV from a bank of FS40 sunlamps. Each UV treatment consisted of an immunosuppressive UV dose, as determined by suppression of contact hypersensitivity to trinitrochlorobenzene, corresponding to about 15-30 min of noonday tropical sunlight exposure under ideal clear sky conditions. Cumulative UV doses were between 80 and 170 kJ/m2. Worm and egg burdens, liver granuloma diameters and liver fibrosis showed minimal changes (< 20%) compared with parameters in unirradiated animals. Ultraviolet irradiation (a total of 55 kJ/m2 administered in six treatments) did not impair the resistance to rechallenge conferred by vaccination with 60Co-irradiated cercariae. We have thus observed a dichotomy between UV immunosuppression and both disease and vaccination in this helminth infection, in contrast to the effects of UVB shown in other infectious diseases.
Noonan
F P
FP
Department of Dermatology, George Washington University School of Medicine, Washington, DC 20037.
Lewis
F A
FA
D000818:Animals; D003877:Dermatitis, Contact / Q000276:immunology; D007109:Immunity / Q000528:radiation effects*; D007165:Immunosuppression Therapy; D051379:Mice; D008810:Mice, Inbred C57BL; D012550:Schistosoma mansoni / Q000528:radiation effects*; D012552:Schistosomiasis / Q000276:immunology* / Q000517:prevention & control; D014466:Ultraviolet Rays