title: Repeated 0.5-Gy gamma-ray irradiation attenuates autoimmune manifestations in MRL-lpr/lpr mice.
abstract: OBJECTIVE
  MRL-lpr/lpr mice, a model for various autoimmune diseases, were repeatedly irradiated with 0.5 Gy of gamma-rays, and changes in their autoimmune manifestations were investigated.
  
  
  METHODS
  MRL-lpr/lpr mice at 13 weeks of age were maintained in plastic cages and exposed whole-body to 0.5 Gy gamma-ray irradiation from a 137Cs source 5 times per week for 4 weeks, from the time they were 13 weeks old until they reached 17 weeks old. Changes of autoimmune manifestations were examined 3 weeks later at the 20th week.
  
  
  RESULTS
  Splenomegaly, lymphadenopathy, and proteinuria in MRL-lpr/lpr mice were clearly ameliorated by a total dose of 10 Gy (0.5 Gy/day x 5 days/week for 4 weeks). Histologically severe disease-specific damage to the kidney and the salivary gland, i.e., glomerulonephritis and sialoadenitis, was also improved after irradiation. CD3+ CD4- CD8- CD45R/B220+ T cell numbers, which proliferate abnormally in MRL-lpr/lpr mice, were significantly decreased by the irradiation, possibly through induction of apoptosis. The elevated NO2- and NO3- (NO(x-) production by macrophages of MRL-lpr/lpr mice was lowered by the irradiation. The irradiation also prolonged the life span of MRL-lpr/lpr mice. These phenomena may contribute to the amelioration of autoimmune manifestations in MRL-lpr/lpr mice exposed to repeated small-doses of gamma-rays.
  
  
  CONCLUSIONS
  Repeated small-dose gamma-ray exposure ameliorates the autoimmune manifestations in MRL-lpr/lpr model mice.
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda-shi, Chiba, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Tanaka
authors.forename: Fumitoshi
authors.initials: F
authors.lastname: Tago
authors.forename: Su-Ping
authors.initials: SP
authors.lastname: Fang
authors.forename: Noriko
authors.initials: N
authors.lastname: Shimura
authors.forename: Shuji
authors.initials: S
authors.lastname: Kojima
mesh_terms: D000818:Animals; D017209:Apoptosis; D015551:Autoimmunity / Q000528:radiation effects*; D049109:Cell Proliferation; D004307:Dose-Response Relationship, Radiation; D005720:Gamma Rays / Q000009:adverse effects*; D008297:Male; D051379:Mice; D019463:Mice, Inbred MRL lpr; D013601:T-Lymphocytes