Human monoclonal antibodies to Pseudomonas aeruginosa type-specific lipopolysaccharides, toxin A and Klebsiella capsular polysaccharides

Abstract

A number of human monoclonal antibodies (HmAb) recognizing type-specific determinants expressed by the lipopolysaccharide (LPS) of Pseudomonas aeruginosa and by the capsular polysaccharide (CPS) of Klebsiella were generated for potential treatment of nosocomial infections. The goal is to administer these type-specific HmAb prophylactically as a "cocktail" providing broad coverage. Lymphoblastoid cell lines (LCL) secreting HmAb recognizing P. aeruginosa LPS, toxin A or Klebsiella CPS were obtained by Epstein Barr Virus (EBV) transformation of peripheral blood lymphocytes (PBL) from donors immunized with either a polyvalent Klebsiella CPS or P. aeruginosa O-polysaccharide-toxin A conjugate vaccine. LCL secreting antibodies of the desired specificities were fused to a heteromyeloma cell line. Stable clones were selected by limiting dilution. Hybridomas secreting IgM HmAb which recognized P. aeruginosa Habs serotype 3 and 4 and all 7 Fisher immunotypes were isolated. All were able to prevent fatal experimental P. aeruginosa sepsis in mice when passively transferred. In addition, 4 lines secreting IgG HmAb which neutralize the cytotoxic activity of toxin A were characterized. IgM and IgA secreting hybridoma cells with specificity for Klebsiella CPS of 22 different serotypes were also isolated. Preliminary studies indicate that these HmAb are opsonic.