Opsonic and protective activity of five human IgM monoclonal antibodies reactive with lipopolysaccharide antigen of Pseudomonas aeruginosa

Abstract International Antigen Typing Schema (IATS) serotypes 1, 2, 5, 6, 8 and 11 comprise approximately vn80% of Pseudomonas aeruginosa strains isolated from blood, wounds and respiratory specimens. Five human immunolgobulin M (IgM) monoclonal antibodies (MAbs) reactive with lipopolysaccharide O antigens of these IATS serotypes were studies in an opsonophagocytic assay. The assay employed human polymorphonuclear leukocytes, 2% guinea pig serum as the complement source and MAb. Each MAb promoted killing of inoculum of the homologous LPS serotype. The opsonic activity of each MAb was complement-dependent. In a murine model of Pseudomonas burn wound sepsis the LD₅₀ of five strains of P. aeuruginosa was increased ≥ 22-fold by MAb-treatment (1.0 mg/kg). The mean effective dose of the five MA0bs in mice challenged with approximately 10 LD₅₀ of the homologous LPS serotype ranged from < 0.01 mg/kg to 1.00 mg/kg.