LPI cells, but not the control cells, isolated from BALF spontaneously form granuloma. (A) While cells from the control BALF did not elongate to a greater degree, many LPI cells became highly elongated. LPI cells then formed granulomas while the control cells remained relatively unchanged (26 days ex vivo). All of these cells moved to one location and eventually formed granulomas over time. The formation of these granulomas was reproducible under different culturing conditions. Images represent randomly selected cells captured every 3-4 days. Bar, 100 μm. (B) Effect of SP-D and GM-CSF on granuloma formation. Treatment of cells with GM-CSF greatly enhanced the formation of granulomatous structures whereas SP-D reduced the effect of GM-CSF-mediated granuloma formation. Non-linear regression analysis and comparison by F-test revealed statistical differences in granuloma formation over the entire experimental period among these four different treatments (p < 0.05).