In vitro studies indicate that tumor necrosis factor-alpha(TNF-α) inhibits the expression of pulmonary surfactant proteins in cell lines. TNF-α is therefore of potential relevance in the neonatal respiratory distress syndrome. We reported the safety of non-bronchoscopic bronchoalveolar lavage (BAL) in 32 preterm and term newborn infants on mechanical ventilation during the first week of life (Pediatr Res 1994;35:325A). BAL was performed with blind wedging of a suction catheter into the right lower lobe bronchus after a short period of pre-oxygenation. Sterile normal saline (at room temperature), 1 ml/kg, was instilled into the lungs. The average volume of saline instilled was 1.5 ml and the average volume recovered was 0.75 ml or 50% of the volume instilled. The collection system was flushed with 2 ml saline and the rinse added to the initial aspirate. Albumin was detected in 30/32 lavage samples, which were then tested for TNF-α. TNF-α titers were quantitated in 96-well microtiter plates by a cytotoxicity assay using L929 (mouse fibrosarcoma) cells. The average albumin concentration of the lung lavage samples was 184 ± 6 μg/mL. TNF-α titers were low during the first 96 h (0-2 U/ml), but started to rise thereafter. Three infants had TNF-α titers of 16 U/ml at 9-12 h of age: two were very preterm infants with severe respiratory distress syndrome who developed severe intra/periventricular hemorrhages and one was a near-term infant with severe respiratory distress syndrome and sepsis following prolonged rupture of membranes. These data suggest that TNF-α concentrations in BAL are low until 4 days after birth and that high TNF-α titers during this period predominate among the sickest and the smallest infants.
