Induction of Opsonic Antibodies to Pseudomonas aeruginosa Mucoid Exopolysaccharide by an Anti-idiotypic Monoclonal Antibody

Abstract

Mucoid strains of Pseudomonas aeruginosa are the major pulmonary pathogens for cystic fibrosis patients. Opsonizing antibodies to the mucoid exopolysaccharide (MEP) antigen may protect animals and some cystic fibrosis patients from infection. However, MEP does not readily elicit opsonic antibodies either during chronic infection or after vaccination. To evaluate alternative means to induce opsonic antibodies, a murine monoclonal anti-idiotypic antibody directed to an opsonic monoclonal antibody specific to MEP was produced. The anti-idiotypic antibody bound to F(ab')2 fragments of the opsonic antibody, blocked binding to MEP, bound to cross-reactive idiotopes on human opsonic antibodies to MEP, and elicited MEP-specific antibodies in syngeneic and allogeneic mice. These anti-idiotype-induced, MEP-specific antibodies fixed complement to mucoid P. aeruginosa cells and opsonized them for phagocytic killing by human leukocytes. These studies demonstrate the potential utility of anti-idiotypic monoclonal antibody for generating protective immunity against bacterial polysaccharides.

Protective Immunization against Group B Meningococci Using Anti-Idiotypic Mimics of the Capsular Polysaccharide

“…After the first demonstration that the antigenic functions of carbohydrates can be mimicked by anti-idiotypic Abs (24), murine mAbs have been successfully used as experimental anti-idiotypic vaccines to induce protective immunity against different encapsulated bacteria (13)(14)(15)25). More recently, short peptides also proved capable of mimicking carbohydrate Ags (12,26,27).…”

γ3 Gene-Disrupted Mice Selectively Deficient in the Dominant IgG Subclass Made to Bacterial Polysaccharides. II. Increased Susceptibility to Fatal Pneumococcal Sepsis Due to Absence of Anti-Polysaccharide IgG3 Is Corrected by Induction of Anti-Polysaccharide IgG1

“…The ability of sera from immunized WT and IgG3 Ϫ/Ϫ mice to opsonize pneumococcus for uptake and killing by human polymorphonuclear leukocytes (PMN) was determined using a modification of an opsonophagocytosis assay as previously described (21,22). Type 3 S. pneumoniae was grown in Todd Hewitt broth with 0.5% yeast extract to a concentration of 1 ϫ 10 8 CFU/ml, resuspended in sterile PBS, and diluted to 1 ϫ 10 5 CFU/ml in RPMI 1640 medium (Life Technologies) with 10% FBS.…”

A Human Anti-Pseudomonas aeruginosaSerotype O6ad Immunoglobulin G1 Expressed in Transgenic Tobacco Is Capable of Recruiting Immune System Effector Function In Vitro

“…Assays for the demonstration of opsonization and associated phagocytosis were performed according to previous publications from the Schreiber laboratory (6,22,30,44,46). Briefly, 10 4 CFU of P. aeruginosa serotype O6ad (International Typing System 011) were mixed with 10 6 fresh human PMN (44) in RPMI medium containing either tobacco-derived anti-P. aeruginosa serotype O6ad IgG (2.5, 12.5, or 25 g/ml), irrelevant control IgG (25 g/ml), or no antibody in 400-l final volumes.…”

“…A small amount of agammaglobulinemic human serum (1.7% final concentration) was used as a source of complement in these assays. After incubation at 37°C for 90 min, treatments were put on ice and then diluted and spread on tryptic soy agar plates (Becton Dickinson Company, Spark, MD) for overnight incubation at 37°C (46). The percent opsonophagocytosis was calculated by using the following formula: 100 ϫ [(number of CFU in the assay without antibody Ϫ number of CFU in a given assay)/number of CFU in the assay without antibody].…”