IL2 and infection: To further establish the immunological mechanism related with the failure of boost strategy against primary infection, the number of CTT3H-specific IFN-γ or IL-2 secreting T cells (Figure 5A), IL-2-expressing TCM (CD62LhiCD44hi) cells, and IFN-γ-positive TEM (CD62LloCD44hi) cells (Figure 5B) in splenocytes between BCG prime-boosted mice was determined.