Inhibitory effect of cystic fibrosis serum on pseudomonas phagocytosis by rabbit and human alveolar macrophages.

This report presents experimental observations indicating the presence of an inhibitory activity 
in cystic fibrosis (CF) serum which impairs phagocytosis of Pseudomonas aeruginosa 
by rabbit as well as human alveolar macrophages. Of the 49 
patient serum samples studied, 40 consistently showed greater than or equal 
to 60% inhibition, 3 showed no inhibition and 6 were in 
the range of 20-60% inhibition of Pseudomonas phagocytosis. In parallel studies, 
the phagocytosis of S. aureus and S. marcescens was found not 
to be inhibited by CF serum. Mixing of CF serum with 
normal serum could not overcome the inhibitory effect, indicating the presence 
of an inhibitory factor rather than the lack of a necessary 
component. The inhibitory activity is not lost upon exposure of serum 
to glass, upon freezing the serum once, or upon heating at 
56 degrees C for 30 minutes. 