CD4 and infection: Further analysis of polyfunctional T-cell responses in different setups– “MIP vaccinated,” “MIP vaccinated + M.tb challenged,” and “only M.tb challenged” animals led to the conclusion that airway lumen of “MIP i.n.” vaccinated animals before infection had a significantly high proportion of 2+ (IFN-γ+ IL-2+) CD4+ T-cells which represent memory cells, but these were not observed post-M.tb challenge.