Figure 6. Association of M. avium spp. isolates with human macrophages.

A. Non-opsonic condition. Macrophage monolayers (2.0×10⁵ cells/well) on glass coverslips in triplicate were incubated in the absence of serum with isolates (MOI 25∶1) for 2 h at 37°C, 5% CO₂. MR-specific association was measured in the presence (close bars) of mannan (2.5 mg/ml). B. Opsonic condition. Macrophage monolayers were incubated with isolates as described above and association assessed in the absence (open bars) or presence (close bars) of 10% fresh autologous non-immune serum. Bacteria associated with macrophages were stained with rhodamine-auramine and association assessed by phase- contrast and fluorescence microscopy. >300 cells/coverslip were counted. Shown are cumulative data from N = 3 (mean±SEM) *P<0.05, *P<0.01, ***P<0.0001.