Protection of mice against P-aeruginosa infections by large-scale affinity-purified human IgG specific to P-aeruginosa outer membrane proteins

In order to develop an effective means to treat Pseudomonas aeruginosa infe ctions, we designed a large-scale process for purification of human IgG spe cific to P. aeruginosa outer membrane proteins (Oprs) from normal human ser a. The process we developed includes affinity column chromatography using P . aeruginosa Oprs as ligands, protein A column chromatography and ultrafilt ration, which enriched P. aeruginosa Oprs-specific IgG antibody by 500-fold . The purified anti-Oprs Ige was specific to the Oprs as confirmed by an EL ISA competition assay and retained opsonophagocytic-killing capacity. In vi vo protective efficacy of anti-Oprs IgG was evaluated by passive protection assays in mice where the 50% protective dose of anti-Oprs IgG against P. a eruginosa infections was 41 mu g/kg, which was 20 times lower than that of normal serum IgG. When administered to mice 3 h after bacterial challenge, only anti-Oprs IgG afforded protection. These data demonstrate the feasibil ity of use of the purification process in producing functionally active tar get-specific human antibodies for clinical use and provide a rationale for use of anti-Oprs IgG as a valuable adjunct to treat P. aeruginosa infection s. (C) 1999 Elsevier Science Ltd. All rights reserved.