Effect of KGF on M. tuberculosis phagosome-lysosome (P-L) fusion in AMs. AMs were isolated from PBS- or KGF-pretreated mice, adhered for 4 h to overnight in a tissue culture chamber slide, and then infected with GFP-expressing M. tuberculosis. After 3 h, infected AMs were washed to remove unbound M. tuberculosis bacilli. AMs were then fixed, permeabilized, stained with LAMP-1 antibody, and processed for confocal microscopy. Shown are representative confocal images of M. tuberculosis-infected AMs isolated from mice that were pretreated with PBS (A) or KGF (B). Phagosome-lysosome fusion was expressed in percentage values and scored by counting the number of intracellular bacilli that fluoresced yellow, representing the co-localization of the GFP-M. tuberculosis (green) with the late endosomal/lysosomal marker LAMP-1 (red) (C). Results are shown as the mean ± S.D. (error bars) of triplicate samples and are representative of three independent experiments. **, p < 0.005 (two-tailed paired Student's t test).