Production of leukocidin by clinical isolates of Pseudomonas aeruginosa and antileukocidin antibody from sera of patients with diffuse panbronchiolitis.

The ratio of leukocidin-producing strains to clinical isolates of Pseudomonas aeruginosa was investigated together with the production of protease, elastase, and exotoxin A. We also examined whether these strains contain the common antigen which resides in the cell wall. By using the agar gel diffusion test with specific antisera, we found that 87 of 90 (96.7%) of clinical isolates produced leukocidin. Protease, elastase, and exotoxin A were also produced at high percentages. The common antigen was found to exist in all strains. Next, to estimate antileukocidin antibody in the sera of patients, we used an enzyme-linked immunosorbent assay with horseradish peroxidase-protein A. The sera of 39 patients with diffuse panbronchiolitis (DPB) were investigated for antileukocidin antibody. The mean antileukocidin titer in the sera of 17 DPB patients who were not infected with P. aeruginosa and 5 DPB patients who were transiently infected with the bacteria was about the same as the mean antileukocidin titer in the sera of 11 healthy controls, whereas the mean antileukocidin titer in the sera of 17 DPB patients who were persistently colonized was significantly higher than that in healthy controls. These results indicate that leukocidin was produced at the local site of infection in DPB patients.