Typical bronchoalveolar lavage differential cell counts in conditions associated with acute respiratory failure and diffuse pulmonary infiltrates
| Condition | Cell differential counts | Comments | |||
|---|---|---|---|---|---|
| Macrophage | Lymphocyte | Neutrophil | Eosinophil | ||
| CFA = cryptogenic fibrosing alveolitis; ARDS = acute respiratory distress syndrome. | |||||
| Normal | 90% | 10% | <4% | <1% | Neutrophils usually <2% in non-smokers |
| Acute interstitial pneumonia | ↑ | ↑ | ↑ | Eosinophils or neutrophils each raised in about 70% of cases of CFA; both being raised is characteristic. Neutrophils may be raised in isolation but this is more typical of infection. Lymphocytes raised in about 10% | |
| Alveolar haemorrhage | ↑ | BAL fluid may be bloody. Haemosiderin-laden macrophages appear after 48 hours and are diagnostic. | |||
| ARDS | ↑ | Neutrophils commonly around 70% of differential count | |||
| Bacterial pneumonia | ↑ | Neutrophils >50% in ventilated patients with bacterial pneumonia | |||
| Eosinophilic pneumonia | ↑↑ | Eosinophils typically 40%, range 20–90%. Neutrophils may also be raised, but always lower than eosinophils | |||