FIG 4.

IL-6 alters macrophage survival in vitro during S. pneumoniae infection. (A) Dynamic changes of IL-6 in the supernatants of WT peritoneal macrophages at the indicated times following S. pneumoniae infection, as measured by ELISA (n = 4 to 6/group). Peritoneal macrophage death was assessed by in situ cell death detection kit in vitro after infection with (B) live (n = 3/group) and (C) heat-killed (n = 3/group) S. pneumoniae. Peritoneal macrophage death was assessed by LDH release (D, n = 6/group; F, n = 5/group) and (E) photomicrographs of cell death (n = 3/group) in the presence and absence of exogenous recombinant mouse IL-6 protein as indicated. (G) IL-1β levels in the supernatants of S. pneumoniae-infected macrophages at the indicated times (n = 4/group).