Clara-cell secretory protein in preterm infants' tracheal aspirates correlates with maturity and increases in infection

Clara-cell secretory protein (CCSP), produced primarily by Clara cells in t he conducting airways, is the most abundant soluble protein in pulmonary la vage fluid. CCSP is thought to be an immunosuppressive or anti-inflammatory protein with protective functions in the respiratory tract against exagger ated inflammatory reactions. CCSP was measured in 98 tracheoalveolar fluid (TAF) samples from 24 preterm infants (gestational age, 27.9 +/- 2.3 weeks, birth weight 1,020 +/- 305 g) with respiratory distress syndrome during th e first 2 postnatal weeks. The ratio of urea-N in serum and in TAF was used to correct for dilution of TAF samples. Concentration of CCSP in TAF when corrected for dilution increased from 3.6 +/- 11 mug/mL on day 1 to 29.6 +/- 6.9 mug/mL on day 14. CCSP correlated w ith gestational age. A negative correlation was found between CCSP and insp iratory oxygen concentration, and a positive correlation between CCSP and b oth arterial pH and base excess during the first 2 postnatal weeks. Infants with clinical and laboratory signs of infection had higher CCSP than nonin fected infants, and a negative correlation was found between CCSP and leuko cyte count during the first 2 postnatal weeks tall P < 0.05). We suggest that pulmonary CCSP correlates with both gestational and postnat al age, and increases in response to infection in infants with respiratory distress during the early postnatal period. Pediatr Pulmonol, 2000; 30:466- 469. (C) 2000 Wiley-Liss, Inc.