Figure 3. Individual Th1 Cells Exhibit a Stable Quantitative Memory for IFN-γ and T-bet Expression.

(A) Experimental set up of (B)–(D). WT recipients of 2 × 10⁵ LCMV-TCR^tg CD4⁺Thy1.1⁺ T cells were infected with LCMV. Thy1.1⁺ cells were reisolated on day 10 and analyzed for T-bet expression (histogram inset; black, staining; gray, isotype control).

(B) Cells were restimulated with LCMV-GP_64–80, sorted by secreted IFN-γ amounts, and cultured.

(C) Frequency of IFN-γ⁺ cells and normalized IFN-γ amount per cell in the sorted fractions on day 4 after sort.

(D) Normalized T-bet amounts per cell on day 4 after sort.

Representative results (B) and means + SD (C, D) of two experiments are shown.

(E and F) In-vitro-differentiated Th1 cells were sorted by secreted IFN-γ amounts and cultured with IL-2.

(E) Frequency of IFN-γ⁺ cells in the sorted fractions.

(F) Normalized IFN-γ amount per cell in the sorted fractions.

Representative results of three (E) and means + SD of two (F) independent experiments are shown.

(G and H) In-vitro-differentiated Th1 cells were sorted by secreted IFN-γ amounts, transferred into WT mice (1.5 × 10⁶ cells/mouse), and reisolated on day 35. Means + SD of two independent experiments are shown.

(G) Frequency of IFN-γ⁺ cells and normalized IFN-γ amount per cell in the sorted fractions.

(H) Normalized T-bet amounts per cell in the sorted fractions.

(I) Experimental setup of (J). WT recipients of 2 × 10⁵ LCMV-TCR^tg CD4⁺Thy1.1⁺ T cells were infected with LCMV. Thy1.1⁺ cells were reisolated on day 10, restimulated with LCMV-GP_64–80, sorted by secreted IFN-γ amounts, and transferred into naive WT mice (5 × 10⁴ cells/mouse). After 16 days, secondary recipients were infected with LCMV. On day 10 after challenge infection, Thy1.1⁺ cells were reisolated.

(J) Frequency of IFN-γ⁺ cells and normalized IFN-γ amount per cell in the sorted fractions are shown (means + SD of n = 3–4 mice).

See also Figures S4 and S5.