Surfactant in children with malignancies, immunosuppression, fever and pulmonary infiltrates

In children with malignancies and immunosuppression, significant morbidity and mortality result from respiratory complications. The aim of the present study was to investigate whether or not this is associated with altered surfactant components or functions. Bronchoalveolar lavage fluid from 24 children with malignancies, immunosuppression, pulmonary infiltrates and fever unresponsive to empirical antibiotic treatment were compared to that from 24 healthy children. Levels of surfactant protein (SP) A and D and their binding capacity for Pseudomonas aeruginosa, as well as levels of SP-B and SP-C, were assessed by enzyme-linked immunosorbent assay. The large and small surfactant aggregate forms were separated and the biophysical activity of large surfactant aggregates was determined using a pulsating bubble surfactometer. Compared to healthy controls, SP-A levels were increased four-fold, the increase being most pronounced in those children with pathogens recovered from their bronchoalveolar lavage fluid. In children with malignancies, levels of SP-C were increased two-fold and of small surfactant aggregates five-fold. No differences were observed in levels of SP-B or SP-D, binding capacity of SP-A or SP-D or the surface activity of large surfactant aggregates. The increased levels of surfactant protein A, particularly in children with recovered microorganisms, and unchanged binding capacity of surfactant protein A are consistent with upregulated local host defence mechanisms. Increased surfactant protein A and C may also be responsible for the conserved biophysical activity of surfactant in children with malignancies, immunosuppression, pulmonary infiltrates and fever.