TUMOR-NECROSIS-FACTOR-ALPHA PRODUCTION DURING CYTOMEGALOVIRUS-INFECTION IN IMMUNOSUPPRESSED RATS

The production of tumour necrosis factor (TNF)-alpha, interleukin (IL) -1 and IL-6, all proinflammatory cytokines, was investigated in radiat ion-immunosuppressed rats infected with rat cytomegalovirus (RCMV). At day 7 post-infection, when the animals showed disease signs, high TNF -alpha levels were detected in the serum and in homogenates of various organ tissues. In contrast, IL-1 and IL-6 levels were not significant ly elevated. Moreover, replication of RCMV induced TNF-alpha expressio n in different types of cells grown in vitro. When frozen tissue secti ons were examined by immunohistology, TNF-alpha-producing cells were f ound in areas with extensive pathology in the lungs, spleen and liver. Both lymphocytes and RCMV-infected cells were identified as the sourc es of TNF-alpha. Its abundance in RCMV-infected rats suggests an impor tant role for TNF-alpha in CMV pathogenesis.