IMMUNOASSAY FOR THE DETERMINATION OF SURFACTANT APOPROTEIN (SP-A) IN HUMAN AMNIOTIC-FLUID - COMPARISON WITH OTHER INDEXES OF ASSESSING FETAL LUNG MATURITY

The concentration of the major surfactant-associated protein SP-A (28-36 kDa) was determined in 73 amniotic fluid samples obtained from normal (n=40) and complicated (n=33) pregnancies. Lecithin/sphingomyelin (L/S) ratio and phosphatidylglycerol (PG) levels were also determined in all the samples by one-dimensional step-wise thin-layer chromatography. An enzyme-linked immunosorbent assay was used to determine human lung surfactant apoprotein SP-A. The amount of SP-A in human amniotic fluid increased as a function of gestational age from 8 mg l-1 at 36 weeks to 11.75 mg l-1 at 40-41 weeks of gestation. There was a significant difference (p<0.01) in amniotic fluid SP-A concentration from female (9.93+/-0.60-mu-g ml-1) compared to male (9.10+/-0.52-mu-g ml-1) foetuses. In amniotic fluid samples obtained from a group of complicated pregnancies, SP-A levels were significantly lower than in the normal group when adjusted for gestational age and sex of the foetus (p<0.05).