FIG. 4.

Foam cell formation by uninfected (solid bars) and C. pneumoniae-infected (open bars) macrophages. Chlamydiae (MOI = 2) were incubated in RPMI medium for 1 h at 4°C (No Rx.), at 100°C (Heat), or with 0.25 M sodium periodate at 37°C (Periodate) before infection, cultured in the presence of 100 μg of LDL per ml, and stained with oil red O. About 500 cells were counted from each well. Data are representative of three experiments and are reported as means of triplicates with SD. ∗, statistically significant difference compared with untreated, infected and heat-treated, infected samples, P < 0.001.