Detection by ELISA of low transferrin levels in bronchoalveolar secretionsof preterm infants

Transferrin levels in bronchoalveolar secretions (BAS) are very low compare d to serum levels in humans. For the exact measurement of transferrin conce ntrations in BAS a very sensitive assay was developed as a double sandwich enzyme immunoassay using the combination of a polyclonal and a monoclonal a ntibody against human transferrin. The measurable range of the assay was 1. 5 to 100 ng/ml of human transferrin. The lowest measurable value was 0.84 n g/ml and the sensitivity of the assay was 0.88 ng/ml. The coefficient of va riation was 14.1% for 25 ng/ml (intra-assay) and 11-20% (inter-assay). The levels measured in 123 samples of BAS of preterm infants ranged between 0.0 3 and 8.93 (mu g/mu g secretory component (SC)). The determination of trans ferrin in BAS of preterm infants is helpful in determining oxidative damage , e.g. the availability of free iron, in the neonatal lung. The transferrin concentration in BAS of neonates who recovered from respiratory distress s yndrome (RDS) in the first six days of life was 0.48 compared to 0.52 ((mu g/mu g SC), median range) for infants who developed chronic lung disease. ( C) 2000 Elsevier Science B.V. All rights reserved.