Gr-1+ PU.1-Null Cells Phagocytose Heat-Killed FITC-Labeled S aureus
| Cell Source* . | Percent of Gr-1+ Cells After Culture-151 . | Percent of Gr-1+ Cells Binding SAFITC -152 . | Percent of Gr-1+ Cells Binding SAFITC After Quenching-153 . |
|---|---|---|---|
| PU.1 normal | 88 | 18 (221) | 16 (217) |
| PU.1 null (#503) | 59 | 20 (87) | 12 (83) |
| PU.1 null (#665) | 62 | 24 (191) | 6 (160) |
| Cell Source* . | Percent of Gr-1+ Cells After Culture-151 . | Percent of Gr-1+ Cells Binding SAFITC -152 . | Percent of Gr-1+ Cells Binding SAFITC After Quenching-153 . |
|---|---|---|---|
| PU.1 normal | 88 | 18 (221) | 16 (217) |
| PU.1 null (#503) | 59 | 20 (87) | 12 (83) |
| PU.1 null (#665) | 62 | 24 (191) | 6 (160) |
*Cells from PU.1-normal or -null neonatal liver were cultured for 2 weeks before use (see Materials and Methods). In a 1-mL volume of Hanks’ balanced Salt Solution, 107 FITC-labeled S aureus (SA) were incubated with 106 normal or PU.1-null neutrophils for 2 hours at 37°C. Samples were washed and then incubated with rat anti–Gr-1PE antibody to identify neutrophils. Samples were then analyzed by two-color flow cytometry for the presence of neutrophils that contained bacteria.
Gr-1 was used to estimate the number of neutrophils in samples from PU.1-normal or -null neonatal liver cultures.
This number reflects the percentage of neutrophils containing detectable SAFITC, whereas the value in parentheses reflects the median channel fluorescence of SAFITC present.
This number represents the percentage of neutrophils containing detectable SAFITC after chemical quenching of cell-bound bacteria (see Materials and Methods), thereby reflecting internalized bacteria protected from chemical quenching, and thus providing a measure of phagocytosis by neutrophils.