FIG. 4.

IFN-γ-producing CD4⁺ T-cell levels specific to viral epitopes in the CNS of P1-Tg mice. (A) CNS-infiltrating MNCs isolated from TMEV-infected mice were restimulated with the indicated mixture of CD4⁺ T-cell-specific epitopes (S mix for cells from B6 mice, VP2_206-220 and VP4_25-38; S mix for cells from SJL mice, VP1_233-250, VP2_74-86, and VP3_24-37). CON represents control cultures similarly incubated with PBS. After a 6-h stimulation, cells were stained for CD4 and intracellular IFN-γ. The percentage of CD4⁺ and IFN-γ⁺ cells is shown at the upper left corner of each plot. Data are representative of two to three independent experiments. d8, d21, and d120 are day 8, day 21, and day 120, respectively. LM, littermate. (B) Histograms represent the mean percentages or numbers from two to three independent experiments by flow cytometric analysis. NS mix is a mixture of two different CD4⁺ T-cell-specific epitopes in the three-dimensional nonstructural protein (RNA polymerase) that are uniquely recognized by TMEV-infected SJL mice (B. S. Kang and B. S. Kim, unpublished observations). The proportion of epitope-specific IFN-γ-producing CD4⁺ T cells (top), total number of CNS-infiltrating CD4⁺ T cells (middle), and number of epitope-specific CD4⁺ T cells in the CNS (bottom) are shown. Statistical significance was analyzed by the Student's t test. *, P < 0.05; **, P < 0.01; and ***, P < 0.001.