Mycobacterium avium Infection of Multinucleated Giant Cells Reveals Association of Bacterial Survival to Autophagy and Cholesterol Utilization

Figure 1

IFN-γ and TNF-α induce formation of multinucleated giant cells in vitro. THP-1 cells were fluorescently labeled after cytokine treatment to determine MGC formation via microscopy at 1000x magnification. The expression of CD40, a marker associated with classical macrophage activation and Langhans giant cells, was measured via flow cytometry. (a) The macrophage fusion index determined the percentage of multinucleated cell having at least 3 nuclei in 10 fields of view. (b) Hoechst stain of MGC nuclei (white arrow). (c) Alexa Fluor Phalloidin 488 stain of actin cytoskeleton (white arrow). (d) Merged image of MGC (white arrow). (e) FITC-CD40 levels in MGCs (black: unstained, blue: isotype control, and red: CD40⁺). (f) FITC-CD40 levels in PMA-differentiated THP-1 cells (black: unstained, red: CD40⁺). (g) Mean fluorescent intensity of FITC-CD40 (black: unstained, blue: isotype control, and red: CD40⁺). All groups were compared to MGC CD40⁺. Data are representative of 3 independent experiments. Statistical comparisons: , , and .

(a)

(b)

(c)

(d)

(e)

(f)

(g)