163 GRP-LIKE IMMUNOREACTIVITY IN BRONCHIAL SECRETIONS OF SURFACTANT-TREATED PHEMATURE INFANTS WITH SEVERE RESPIRATORY DISTRESS SYNDROME (RDS)

Abstract

Gastrin-releasing peptide (GRP) and GRP-related peptides are putative growth factors. Existence of GRP-like immunoreactivity (IR) has not been examined in bronchioalveolar secretions of the neonate. We have analyzed bronchial fluid of 54 premature infants (26-33 weeks of gest.) with severe RDS (FiO2 > 0.8, mechanical ventilation). Sequential samples (n = 290) were obtained within 1 week after surfactant (S) replacement therapy (single or multiple doses; total amount of phospholipids 200 vs. 400 mg/kg bw). GRP-like IR was determined by radioimmunoassay. Results: In 32/54 patients (59%) GRP-like IR could be detected. Concentrations were 0,3-70 ng/mg albumin (a). Neither gestational age, birthweight, sex nor severity of pulmonary disease did correlate with the amount of GRP-like IR detected. In 13/24 samples (54%) of single-dose-S-treated infants GRP-like IR was found (x = 3,16 ng/mg a); in multiple treated infants 18/30 probes (60%) were GRP-positive (x = 4,47 ng/mg a). Further HPLC characterization of the GRP-like IR suggests the existence of different molecular forms of GRP-like peptides. Conclusions: GRP-like IR can be detected in bronchial fluid of premature infants with severe RDS. Multiple doses of surfactant do not influence the GRP content. The physiological role of GRP-like peptides in the developing respiratory tract of the neonate has not been defined yet.