Kinetics of fever and its related cytokines in mice after intraperitoneal infection with listeria monocytogenes

1. 1. We studied the kinetics of fever and its related cytokine production in mice after an intraperitoneal (i.p.) infection with a sublethal dose of viable Listeria monocytogenes. By day 2 after an inoculation of Listeria, body temperature of the infected mice rose to a higher level than that of non-treated mice. On day 3 after infection, body temperature of the mice became lower than that of non-treated mice, and was accompanied by wasting. After day 5, the mice gradually recovered from this wasting to show a similar level of body temperature to the control mice. 2. 2. The number of peritoneal exudate cells (PEC) increased to the maximal level on day 3, when Thy1/CD3-positive cells emerged, and then the T cells increased to 35% of the non-adherent population of the PEC on day 8. By contrast, the number of IgM⁺- or Ly1⁺-positive cells was at a constant level (∼60%) and ∼20%, respectively) of the non-adherent PEC during the infection. 3. 3. To characterize the productive pattern of fever-related cytokines in listeriosis, we investigated their expression in the PEC from mice during infection. In the adherent-PEC, IL-1α and IL-6 mRNAs were consistently expressed from day 1 to day 8 after infection, while TNF had already been expressed at the highest level on day 1 and decreased on day 8. IFN-γ mRNA was first detected in the non-adherent PEC on day 3 and increased on day 8. 4. 4. These results suggest that TNF may be related to the initial febrile state and the consecutive wasting at the early phase of listeriosis, followed by the T-cell expansion producing IFN-γ for elimination of Listeria.