To obtain a direct evidence that CD8+ T cells of HLA-A2.1-transgenic mice have greater IFN-γ responses to T. gondii infection than those T cells of WT mice do, we examined the numbers of IFN-γ-producing CD8+ T cells in the spleens of HLA-A2.1-transgenic and WT mice using flow cytometry at 4-5 weeks after infection. The gene discussed is CD8A; the disease is infection.