Figure 2. Expansion and differentiation of Se epitope-specific Th1 cells in Seinfected mice.

(A)Plots of LpdAp:I-A^b-specific CD4⁺ T cells from uninfected (left) or Se-infected (right) mice 60 days after infection identified by tetramer-based cell enrichment and flow cytometry. (B)Mean numbers (± S.D.) of LpdAp:I-A^b tetramer⁺ CD4⁺ T cells in the indicated organs of 129 mice at the indicated times after Se infection. (C)Representative histograms showing intracellular T-bet staining of CD44^low naïve CD4⁺ T cells and CD44^high LpdAp:I-A^b tetramer⁺ CD4⁺ T cells from the same Se-infected mouse. (D)Representative contour plots of LpdAp:I-A^b tetramer⁺ CD4⁺ T cells from day 60 Se-Tomato infected 129 mice. (E)Mean numbers (± S.E.M., n ≥ 3 mice per group/timepoint) of LpdAp:I-A^b tetramer⁺ CXCR3⁺ or CX₃CR1⁺ CD4⁺ T cells in the spleens of 129 mice at the indicated times after Se infection. Significance was determined on log-transformed values using twoway ANOVA with Sidak’s multiple comparisons post-test (** p < 0.01, *** p < 0.001, **** p < 0.0001). (F)Mean CFU (± geometric S.D.) per spleen from 129 mice that received total (n = 4), CXCR3⁺ (n = 5), CX₃CR1⁺ (n = 4), or no CD4⁺ memory T cells (n = 5) from day 60 Se-infected 129 mice, seven days after intravenous infection with 10⁴ Se-Tomato bacteria. Log-transformed values were compared using one-way ANOVA with Tukey’s multiple comparisons post-test (* p < 0.05, *** p < 0.001, **** p < 0.0001, n.s. = not significant) and is derived from three independent experiments.