Trafficking and maintenance of CD8⁺ T cell response to <i>T</i>. <i>cruzi</i> in peripheral tissue.

(A) CD8+ T cells are recruited from a central pool to non-lymphoid tissues in chronic T. cruzi infection. CD8+ T cells were magnetically purified from infection-matched CD45.1+ donor mice (>100 dpi) and transferred into CD45.2+ recipient mice. Cells were isolated from spleen (square) and skeletal muscle (triangle) at various time points after transfer. Mean ± SEM of two samples analyzed at each time point is shown and represents data obtained in three independent experiments. (B) Interruption of leukocyte trafficking is detrimental to parasite control. Mice (>100 dpi) were treated with a blocking anti-VLA-4 Ab for 30 days, and parasite load was determined in skeletal muscle. * indicates p+ T cells are enriched in tissues of parasite persistence. Mice chronically infected with T. cruzi were given BrdU in their drinking water for 21 days. Lymphocytes were then isolated from lymphoid and non-lymphoid tissue. Histograms describe BrdU incorporation by splenic (blue) and muscle-derived (teal) CD8+ T cells in the total (left) and TSKB20+ (right) population. These data are summarized in accompanying column graph (right). (D) Dividing CD8+ T cells develop into activated effectors at sites of parasite persistence. Expression of CD69 was examined among proliferating (BrdU+) CD8+ T cells in muscle and spleen in naïve animals and mice with chronic T. cruzi infection on day 21 of BrdU administration. Data in panels C and D are mean + SEM and are representative of two independent experiments with n = 4–5. * indicates values that are significantly different (* P ≤ 0.05, ** P ≤ 0.01, ***P ≤ 0.001) between compared groups.