Figure 8.

M. tuberculosis PIM causes transferrin receptor accumulation on latex bead phagosomes. Shown is confocal microscopy of latex bead phagosomes in J774 cells. (A and D) Green fluorescence of latex beads. (B and E) Red immunofluorescence of transferrin receptor. (C and F) Merged images of green and red fluorescence. Latex beads were coated with purified M. tuberculosis H37Rv PIM and phagocytosed by J774 cells for 30 min. On phagocytosis, cells were fixed, permeabilized, and labeled with anti-transferrin receptor antibody followed by Alexa-568-conjugated secondary antibody. Arrowheads indicate colocalization of latex beads with transferrin receptor. Quantitation of transferrin receptor colocalization is shown numerically in G. The data are means ± SE of three separate experiments (n = 400 for control and n = 400 for PIM).