CD8A and infection: To demonstrate that CD8+ T cells activated by recognition of T. gondii antigens presented by the HLA-A2.1 confer a protection against reactivation of infection with this parasite, CD8+ immune T cells (2 x 106 cells) purified from the spleens of infected HLA-A2.1-transgenic and WT mice were systemically transferred to infected, sulfadiazine-treated immunodeficient NSG mice expressing the HLA-A2.1.