Am. J. Respir. Crit. Care Med., Vol 150, No. 6, Dec 1994, 1672-1677.
Surfactant protein A and saturated phosphatidylcholine in respiratory distress syndrome
FR Moya, HF Montes, VL Thomas, AM Mouzinho, JF Smith and CR Rosenfeld
Department of Pediatrics, University of Texas Southwestern Medical Center at Dallas 75235.
We measured surfactant protein A (SP-A) by ELISA using a rabbit antihuman
SP-A polyclonal antibody and saturated phosphatidylcholine (SPC) by
thin-layer chromatography in sequential tracheal fluid samples obtained
from 16 preterm neonates without lung disease and 37 with respiratory
distress syndrome (RDS). SP-A and SPC were lower in neonates with RDS than
in control infants (1.0 +/- 0.1 versus 8.9 +/- 2.2 ng SP-A/microgram
protein [p < 0.0001] and 0.20 +/- 0.05 versus 0.70 +/- 0.19 mumol SPC/mg
protein [p < 0.01], respectively). Initial SP-A concentrations
correlated inversely with severity of RDS (r = 0.45, p < 0.01) but did
not correlate with initial SPC levels. Significant increases in SP-A were
detectable within 12 to 24 h after birth in neonates with RDS. Further
increases occurred subsequently and were similar for neonates treated with
either a synthetic (Exosurf) or a modified natural (Survanta) surfactant.
Using two-dimensional gel electrophoresis, SP-A in tracheal fluid obtained
during the early and recovery phases of RDS exhibited lesser degrees of
posttranslational modification than SP-A forms from control neonates.
Administration of Exosurf or Survanta resulted in comparable increases in
SPC in tracheal fluid. Preterm neonates with RDS seem to have an immature
SP-A metabolism that persists for several days after birth. The type of
surfactant used does not modify the recovery of SP-A or SPC in tracheal
fluid from infants with RDS.
