Time requirements of T cell help and the role of Tregs cells.

(A) 2×104 CD8+ T cells were transferred into CD3ε−/− hosts. At 8 or 29 days after groups of hosts received CD4 T cells (2×104 cells) and the mice were sacrificed 7 weeks after the first cell transfer. The mean CD8+ T cell recovery is shown for the three groups of hosts (***p≤0.001). It should be pointed out that the late transfer of CD4 T cells still induced the preferential accumulation of CD62LlowCD8+ TEM cells (not shown) (B) 2×104 CD8+ T cells were transferred alone or with CD4+ T cells from Lat-DTR mice into a CD3ε−/− host. A fraction of the mice were treated with diphtheria toxin (DT) for 10 days at either one or 4 weeks after cell transfer, and the mice were analyzed 7 weeks after cell transfer. The number of CD8+ T cells recovered 7 weeks after cell transfer is shown. CD4+ T cell depletion at week 1 or at week 4 reduced the number of CD8+ T cells recovered (**p≤0.01). Similar findings were obtained in two independent experiments. Dot plots show representative examples of the CD62L and CD44 expression by the CD8+ T cells recovered in the different groups of mice. (C) 104 CD8+ T cells were transferred into CD3ε−/− hosts alone or with 5×104 CD4 Treg cells. The number of CD8+ T cells recovered in individual mice is given as the mean value for each group. (D) 104 CD8+ T cells were transferred into CD3ε−/− immune-deficient hosts alone, co-transferred with 104 CD4naive T cells or co-transferred with 104 CD4naive T cells and 5×104 CD4 Treg cells in three independent groups of hosts. The number of CD8+ T cells recovered in individual mice is given as the mean value for each group. The increased expansion of CD8+ T cells seen upon co-transfer with CD4naive T cells was abolished when the Treg cells were added in the transferred mix. (**p≤0.01) (E) 105 total CD8+ T cells were transferred into CD3ε−/− hosts alone, co-transferred with 104 CD4naive T cells or co-transferred with 104 CD4 T cells and then given 5×104 Treg cells four weeks latter. Mice were culled 8 weeks after the initial CD8+ T cell transfer. The data indicate the number of CD8+ T cells recovered in each host. Statistically significant differences are shown (**p<0.01). Similar findings were obtained in two independent experiments.

Categories

Keyword(s)

License

CC BY 4.0