Apoptosis Is Essential for Neutrophil Functional Shutdown and Determines Tissue Damage in Experimental Pneumococcal Meningitis
Figure 4
Overexpression of Bcl-2 preserves neutrophil effector functions upon SCF withdrawal.
Effector functions of wt or Bcl-2-overexpressing neutrophils differentiated for 5 days were compared with that of Bcl-2 neutrophils differentiated for 5 days and then cultured in the absence of SCF for 48 hours. In all experiments Streptococcus pneumoniae and neutrophils were co-incubated at a ratio of 100∶1. (A) Phagocytic uptake of FITC-labelled pneumococci was analysed by flow cytometry after 1 hour co-incubation. Very similar results were seen in 3 independent experiments. (B) Production of reactive oxygen species was measured by the capacity of neutrophils to oxidise dihydrorhodamine. Cells were incubated for one hour with pneumococci (bold line) or with PMA (5 µg/ml, dotted line). Unstimulated cells are shown as shaded histogram. Very similar results were seen in 3 independent experiments. (C) Secretion of IL-1β was measured in supernatants of neutrophils stimulated with pneumococci for 8 hours. Data are mean/SEM of four independent experiments.