Experimental neonatal respiratory failure induced by a monoclonal antibody to the hydrophobic surfactant-associated protein SP-B.

The present experiments were designed to test whether selective blocking of the surfactant-associated hydrophobic polypeptide SP-B (8.7 kD) would interfere with lung function during neonatal adaptation. A MAb to porcine SP-B was produced by hybridoma cell line (8B5E); this antibody cross-reacts with rabbit SP-B. Six mg of MAb to SP-B, dissolved in 0.2 mL of saline, was instilled into the airways of near-term newborn rabbits (gestational age 29 d), before the onset of ventilation. Control animals received the same amount of nonspecific rabbit IgG in saline, or were untreated. The animals were ventilated for 120 min with a standardized tidal volume (10 mL/kg). The specific antibody caused a prominent, immediate decrease in lung-thorax compliance, associated with acute inflammatory and exudative lung lesions including hyaline membranes. IgG alone had no such effects. Our data suggest that the MAb to SP-B inhibits surfactant function in the neonatal period by blocking one of the mechanisms responsible for fast adsorption of the surfactant phospholipids to the alveolar air-liquid interface. In addition, an acute inflammatory reaction is probably triggered in the lung parenchyma by the immune reaction.