INDUCTION OF OXIDATIVE BURST RESPONSE IN HUMAN NEUTROPHILS BY IMMUNE-COMPLEXES MADE IN-VITRO OF LIPOPOLYSACCHARIDE AND HYPERIMMUNE SERUM FROM CHRONICALLY INFECTED PATIENTS

Purified lipopolysaccharide (LPS) from Pseudomonas aeruginosa was used as an antigen for immune complex (IC) formation in vitro together wit h hyperimmune sera from chronically P aeruginosa-infected patients wit h cystic fibrosis (CF). P aeruginosa LPS by itself did not induce an o xidative burst in human neutrophil granulocytes (PMN)s measured by che miluminescence (CL). This was also the case using hyperimmune CF serum alone. In contrast, P aeruginosa LPS together with CF serum did induc e a CL response. The CL responses varied depending on the sera used fo r IC formation, and were reduced when protein A preabsorbed sera were used. PEG precipitation of the ICs from the mixture increased the CL r esponse. These findings indicate that the CL responses induced by the mixture of P aeruginosa LPS and CF serum were due to IC formation and an Fc-mediated stimulation of the PMNs. It is concluded that ICs made from sera of chronically infected CF patients and purified P aeruginos a LPS are biologically active in terms of activating PMNs, and may con tribute to the lung tissue damage seen in this group of patients.