A rapid and simple method for evaluation of serum opsonic capacity against Bordetella pertussis by chemiluminescence

Serum opsonic capacity against Bordetella pertussis was studied by using quantitative chemiluminescence (CL) which is known to have several advantages over conventional methods in the evaluation of opsonization and phagocytosis. For opsonization, sera from whooping cough patients or from controls were incubated with killed B. pertussis cells at 37 degrees C for 30 min. Polymorphonuclear leukocytes, mononuclear cells or unfractionated leukocytes, all from healthy blood donors, were added to the opsonization mixture and CL emission was measured. Bacteria opsonized in diluted sera of whooping cough patients caused the activation of leukocytes manifested as a CL emission and no CL emission was observed when unopsonized B. pertussis was incubated with leukocytes. The opsonins could be detected by using any type of leukocyte preparation. Sera from adults vaccinated with DTP in the childhood gave rise to a large CL emission. Sera from whooping cough patients produced CL responses in more dilute solutions than those from vaccinated controls and sera from unvaccinated infants did not contain opsonins against B. pertussis. In unvaccinated infants suffering from whooping cough no opsonins were detectable in sera collected one week after the onset of the disease. However, the development of the opsonic capability against B. pertussis was observed in follow-up sera of all patients. The CL assay is simple, rapid, and reproducible offering new possibilities to evaluate humoral immune mechanisms and phagocytosis in whooping cough.