Substantial ex vivo IFNγ production by CD8+ cells from LCMV-infected mice. (A) B6 and Kb−/−Db−/−CIITA−/− mice were infected with 2 × 105 PFUs LCMV-Armstrong and, at days 3, 5, 8, and 12, spleens were harvested and analyzed for surface CD8〈 and intracellular IFN© by flow cytometry. (B) The percentage and total number of IFN© producing CD8α+ spleen lymphocytes was determined for B6, and Kb−/−Db−/−CIITA−/− mice at various time points post infection.