Fig. 3

Immunofluorescence analysis of the late endosome and lysosome in macrophages infected with L. pneumophila. J774A.1 cells were incubated with the wild-type L. pneumophila or mutant strains for 2 h, then fixed and stained with a monoclonal antibody specific to LAMP-1 or TroV to identify the macrophage late endosomes or lysosomes. a Phagosomes containing wild-type strain Lp02pj were not co-localized with late endosomes, whereas phagosomes containing Xp02pj or Lp03pj were stained and colocalized with LAMP-1. b Meanwhile the percentages of L. pneumophila-containing phagosomes fused with the late endosomes were determined. **, p < 0.01. c The fusion of phagosomes with lysosomes was also examined using confocal microscopy and d quantified as above. **, p < 0.01. The immunofluorescence assay was carried out in triplicate. Shown are the averages and standard deviations of three independent counts. The number of J774A.1 cells for each count is about 100