CD8B and infection: To determine whether non-M3, MHC Ib-restricted CD8+ T cells mediated the protective effect observed in Mtb-infected Kb-/-Db-/-M3-/- mice, Mtb-infected Kb-/-Db-/-M3-/- mice were repeatedly treated with anti-CD8β mAb or control Ab and the bacterial burden in the lungs of these two groups of mice were compared at day 30 post-infection.