IL1B and tuberculosis: Giving that macrophages from parental I/St and A/Sn strains displayed intrinsic differences in the expression of inflammatory genes, and that the same two cytokines, IL-1β and IL-11, were highly expressed in “susceptible” I/St macrophages, and in the lungs of F2 mice with severe TB, we believe that the second explanation is more likely, i.e. the intensity of inflammatory response mounted by infected F2 mice were controlled genetically.