This study was performed to evaluate differences of immune responses according to the injection period of recombinant mouse interferon-γ(IFN-γ)in acute murine toxoplasmosis. Each mouse was infected intraperitoneally with 100 cysts of Beverley
strain
of T. gondii, and injected with 5×104 units of IFN-γ-every other day for a total of two injections. From the 1st week after infection, blastogenic responses of splenocytes to concanavalin A(Con. A, 2.5μg/ml) and Toxoplasma antigen(30.0μg/ml)
were
examined at 1 week interval for 4 weeks. Also serum IgG and IgM antibody titers were examined by enzyme-linked immunosorbent assay, and immunohistochemical study of brain tissues were done at the same time. Toxoplasma antigen-treated blastogenic
responses were significantly increased in the IFN-γ injected groups as compared with Toxoplasma-infected group. however Con. A-treated blastogenic responses were increased in the mice that received two doses of IFN-γ on day 4 and 2 before
infection,
or day 2 and 0 before infection. The serum IgG and IgM antibody titers of IFN-γ injected groups were increased from 2 weeks after infection, and IgM antibody titers were increased at 2 and 3 weeks after infection as compared with non-infected
group. No
significant differences were revealed between. IFN-γ injected group and Toxoplasma-infected group. T. gondii was found as tachyzoites at 2 weeks after infection, and cysts found in 4 weeks. However, no T. gondii was detected in IFN-γinjected
groups in
the same period. The results suggested that IFN-γ administration to T. gondii-infected mice improve the cell-mediated immune responses, especially when IFN-γwas injected just before. T. gondii infection. But there was not significant difference
serum
antibody titers and immunohistochemical findings of brain tissues according to the injection period of IFN-γ.
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