UV-B irradiation increases susceptibility of mice to malarial infection.
We here examined whether exposure of mice to UV-B affected their susceptibility to the murine malaria parasite Plasmodium chabaudi. When BALB/c mice with depilated skin were irradiated with UV-B and subsequently infected with the parasite, 80 to 100% of the UV-B-irradiated mice died within 12 days of infection with a sublethal dose. In addition, UV-B irradiation of C57BL/10 (B-10) mice, which are otherwise naturally resistant to the parasites, rendered them susceptible, and 100% of irradiated B-10 mice died within 11 days postinfection. The level of plasma gamma interferon (IFN-gamma) in unirradiated B-10 mice at 5 days after infection increased to 566 pg/ml, whereas the UV-B exposure of mice impaired the production of IFN-gamma, which showed a maximum level of 65 pg/ml in response to the parasite infection. The maximum level of plasma interleukin-10 in UV-B-irradiated mice in response to the parasite infection was approximately 1,100 pg/ml, which was approximately fourfold higher than the maximum level in unirradiated control mice. When UV-B-irradiated B-10 mice were administered murine recombinant IFN-gamma after infection, the mice regained parasite resistance. These results demonstrated that the UV-B exposure of mice enhances the susceptibility to the malaria parasites and suggested that the enhanced susceptibility following UV-B exposure was mediated by impairment of IFN-gamma production in response to the parasite infection.
Yamamoto
K
K
Department of Virology I, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo 162-8640, Japan. yamamoto@nih.go.jp
Ito
R
R
Koura
M
M
Kamiyama
T
T
D000818:Animals; D004198:Disease Susceptibility; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D007371:Interferon-gamma / Q000097:blood / Q000494:pharmacology; D016753:Interleukin-10 / Q000097:blood; D008264:Macrophages / Q000528:radiation effects; D008288:Malaria / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D013997:Time Factors; D014466:Ultraviolet Rays
D016753:Interleukin-10; D007371:Interferon-gamma