Levels of SP-A-anti-SP-A immune complexes in neonatal respiratory distress syndrome correlate with subsequent development of bronchopulmonary dysplasia

As part of a double-blind, randomized, placebo-controlled study of human surfactant therapy for neonatal respiratory distress syndrome (NRDS), we measured circulating immune complexes between surfactant protein-A and anti-surfactant protein-A antibodies (SAS). Plasma from almost all infants contained detectable immune complexes. Immune complex levels in surfactant-treated infants were comparable with those of placebo-treated controls. Despite the relatively small sample size, maximum SAS immune complex values between 2 and 4 weeks after birth correlated significantly with subsequent development of BPD. Levels of these immune complexes correlated with eventual BPD independently of, and more strongly than, gestational age and birth weight. Thus, plasma SAS immune complex measurements may be useful in analyzing the course and outcome of NRDS, in particular the likelihood of subsequent development of BPD. This assay may also help to identify infants at risk for BPD and to target preventative therapy to them.