Early and robust LCMV-specific granzyme B production by CD8 T cells during LCMV infection in Kb−/−Db−/−CIITA−/− mice. Splenocytes from LCMV-infected B6, and Kb−/−Db−/−CIITA−/− mice were stained on the surface for CD8〈 and TCR®, then intracellularly for granzyme B and analyzed by flow cytometry. (A) The percentage of granzyme B producing CD8α+TCRβ+ splenocytes from B6 and Kb−/−Db−/−CIITA−/− mice at day 3, 5, 8 and 12 post LCMV-Arm infection. (B) The mean fluorescence intensity (MFI) of granzyme B expression on the CD8〈+TCR®+ cells at day 3, 5, 8 and 12 post infection.