Diverse VH and V kappa genes encode antibodies to Pseudomonas aeruginosa LPS

The molecular nature of the murine Ab response to Pseudomonas aeruginosa LPS was examined using a panel of 10 well-defined anti-LPS mAbs. Abs to P. aeruginosa LPS are encoded by diverse V-genes, with at least five VH and four V kappa gene families represented in these Abs. The Abs that bind to hydrophilic O-polysaccharide side chains of B-band LPS and A-band LPS are encoded by VH J558, SM7, and J606 gene families, while Abs to hydrophobic core and lipid A regions are encoded by X24, SM7, and Q52 gene families. All active JH and only two J kappa (J kappa 2 and J kappa 5) germ-line genes are utilized in the anti-LPS Abs examined. Four of six anti-P. aeruginosa mAbs used diversity genes of the DSP2 gene family. Interestingly, JH1 and JH2 use was observed in three mAbs that reacted with hydrophilic LPS epitopes (O-polysaccharide, A-band LPS), whereas JH3 and JH4 use was observed in three mAbs that bound to the more hydrophobic regions of LPS (core, lipid A). Point mutations were observed in framework and complementarity-determining regions (CDRs) of VH and VL genes, suggesting an Ag-driven maturation process in response to P. aeruginosa LPS. Mutations occurred in all heavy chain CDRs, as well as in CDR1 and CDR3 of the light chain, indicating an important role of these regions in binding to LPS. These data suggest that diverse VH and V kappa genes encode Abs to LPS from P. aeruginosa.