Quantification of proteins in bronchoalveolar lavage fluid (BALF) is being performed increasingly, because of their potency in elucidating pathophysiological processes and their possible clinical relevance.
Study population: 37 normal children (12 female, 25 male, mean age +/- SD 7.9 +/- 3.5 years, range 3-16 years) undergoing elective surgery for nonpulmonary illnesses and 16 healthy adults (all male, mean age +/- SD 24.7 +/- 2.6 years, range 20-28 years, 8 smokers, 8 nonsmokers) have been studied after approval by the ethics committees of both institutions.
Methods: BAL was performed with normal saline in the right middle lobe or one of its segments. Lavage volume was 15 x 20 ml in adults and 3 x 1 ml/kg in children. In adults the first aliquot was processed separately, 2 aliquots of the following were pooled (resulting in 8 different fractions) so that different lavage protocols could be calculated. The concentrations of the plasma-proteins alpha 1-proteinase inhibitor (alpha-1PI), alpha 2-macroglobulin (alpha 2PI), albumin (Alb) and of the locally released proteins myeloperoxidase (MPO), lactoferrin (Lf), elastase (Ela) and fibronectin (Fib) were determined in BALF using chemiluminescence immunoassays.
Results: The BALF concentrations of the plasma proteins were higher in children compared to adults. In contrast, concentrations of the locally released proteins were similar in both groups. Protein concentrations in the first recovered aliquot were different from the following in healthy adults with higher values of MPO, Lf and Ela and lower concentrations of alpha 1PI, alpha 2PI and Alb. Subsequent aliquots did not show a progressive dilution of these proteins with increasing lavage volumes. In smokers, BALF concentrations of albumin, alpha 1PI and MPO were higher compared to nonsmokers.
Conclusion: BALF protein concentrations are different in normal children and adults. These results underscore the necessity to establish independent reference values for children, as could be demonstrated earlier with regard to BAL cell composition.