FIG. 7.

Effect of anti-GM-CSF and anti-G-CSF neutralizing antibodies on delayed spontaneous apoptosis induced by GM-CSF, G-CSF, or conditioned medium from infected fibroblasts. Neutralizing or isotype control antibodies were preincubated for 1 h with 10 pg of GM-CSF/ml (A) or 850 pg of G-CSF/ml (B) and then added to neutrophils. A 1:80 final dilution of conditioned medium from infected fibroblasts (C) was preincubated with 1 μg of neutralizing or isotype control antibodies/ml for 1 h and then added to neutrophils. Neutrophil apoptosis was determined 18 h later by flow-cytometric analysis of staining with GFP-annexin and PI. Spontaneous apoptosis, seen with 1 μg of isotype control antibody/ml, or medium alone, is shown as a dotted line. Asterisk, statistically significant difference (P < 0.001) by a one-way analysis of variance test. Results are reported as the mean ± standard deviation of triplicate samples and are representative of two experiments for cytokines and four experiments for conditioned medium from infected fibroblasts.