Fig 8. H₂O₂ hinders phagosome-lysosome fusion.

(A) RAW cells were treated with H₂O₂ or vehicle (H₂O) for 1h before introducing ZsGreen-expressed E. coli (green). RAW cells were incubated for 20 minutes in the presence of bacteria and H₂O₂ or vehicle, then RAW cells were washed with PBS, and further incubated in media containing H₂O₂ or vehicle for an additional 40 minutes. External bacteria were labeled with rabbit anti-E. coli antibodies (blue) and were excluded from analysis using a mask. LAMP-1 was labeled with rat anti-LAMP-1 antibodies (red). (B) Quantification of mean LAMP-1 intensity on bacteria-containing phagosomes. LAMP-1 intensities were quantified from regions that co-localized to internal bacteria (green signal and no blue signal). Data represented as a scatter plot, where each dot is an individual phagosome from n = 144 to 179 cells across all independent experiments and conditions. Mean ± standard deviation from three independent experiments is indicated as well. Data analyzed with two-tailed unpaired t-test (* indicates p<0.05).