In immunocompetent rats and humans infection with Toxoplasma gondii remains mostly without overt clinical symptoms, but can be fatal, if the T-cell response is impaired. For a better understanding of the lack of control of T. gondii infection under immunosuppressed conditions, congenitally athymic rats were used as the experimental model. Whereas athymic F344-Whn(rnu) (F344 nude) rats die from a generalized infection during the first 3 weeks after peritoneal inoculation with 10(6) tachyzoites of T. gondii strain NTE, LEW-Whn(rnu) (LEW nude) rats and euthymic LEW rats infected with a 10-fold higher number of parasites developed chronic infection. To identify underlying mechanisms of LEW rats resistance to T. gondii infection and to investigate a possible contribution of residual T-cells to LEW-Whn(rnu) rat resistance, we characterized the immune response of LEW rats by determination of cellularity and composition of lymphocyte population, antigen-specific IgG2b response as well as assays of antigen-specific proliferation and production of IL-2, IFN-gamma and TNF-alpha. As only euthymic LEW rats developed production of antigen-specific IgG and cellular in vitro responses, these results strongly suggest that the genetic background of LEW rats permits a control of the infection independent of an adaptive immune response.

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immune response tcells toxoplasma lewwhnrnu rat cellularity cellular composition of lymphocyte population antigenspecific igg2b response t gondii antigenspecific proliferation il2 ifngamma and tnfalpha

J C, Sepulveda-Arias M C, Kempf S, Wiehr D, Wedekind H J, Hedrich U, Gross T, Herrmann,.Control of Toxoplasma gondii infection by athymic LEW-Whn rnu rats.. 30 (6-7),323-33.

J C, Sepulveda-Arias M C, Kempf S, Wiehr D, Wedekind H J, Hedrich U, Gross T, Herrmann,"Control of Toxoplasma gondii infection by athymic LEW-Whn rnu rats." 30

J C, Sepulveda-Arias M C, Kempf S, Wiehr D, Wedekind H J, Hedrich U, Gross T, Herrmann,"Control of Toxoplasma gondii infection by athymic LEW-Whn rnu rats."