Innate CD8⁺ thymocytes induce protection during <i>T</i>. <i>cruzi</i> infection in an Ag-independent manner.

(A) CD8αKO, OT-I and WT mice were infected with 5000 T. cruzi parasites (Tulahuen) (recipient mice). In the WT-AT group, a bulk suspension of 10 x 106 thymocytes from T. cruzi- infected mice was adoptively transferred (AT) to WT B6 mice 24h prior to infection with 5000 T. cruzi parasites. Survival was compared between groups and monitored at different time points after infection. WT+AT, WT or OT-I vs CD8KO, *p.05, **p.01 (B) WT mice were not AT (Non-AT) or AT with sorted 5–6 x 106 SP8 thymocytes from OT-I T. cruzi-infected (Tulahuen) mice (AT-OTI) 24h prior to the infection with 5000 T. cruzi parasites and monitored for survival daily post infection (C) Parasitemia (number of parasites per ml of blood) of non-AT or AT-OTI was evaluated on days 10, 13 and 16 post infection. (D) Non-AT mice or mice AT with a bulk suspension of 10 x106 thymocytes from IL-12+IL-18 cDNA-treated mice (AT-12+18) were monitored for survival in the days post infection with 5000 T. cruzi parasites. (E) Parasitemia of non-AT or AT-12+18 was evaluated on days 10, 13 and 16 post infection. Data represent two replicates of the same experiment with 6–8 animals per group. The number of parasites was compared with a One-way ANOVA test and survival data were analyzed with the Wilcoxon-Gehan-Brelow test. Non-AT versus OTI-AT or AT-12+18, *p.05. NS: not significant. WT = conventional C57BL/6 mice.