Role of IgG subclass response to outer-membrane proteins in inhibiting adhesion of Pseudomonas aeruginosa to epithelial cells.

Abstract

The IgG subclass response to the major outer-membrane proteins (OMPs) of Pseudomonas aeruginosa was investigated in 11 cystic fibrosis (CF) patients and 10 healthy controls. Inhibition of adhesion of P. aeruginosa to buccal epithelial cells by the IgG serum fractions from the CF patients has been established previously. The CF patients demonstrated marked heterogeneity in their individual IgG subclass response to pseudomonal OMPs. The predominant IgG1 and IgG4 responses were directed towards OMPs F, H2 and, with IgG1 only, to protein I. Proteins of 42 and 46 kDa primarily elicited an IgG2 response but some patients produced IgG4 antibodies. The IgG3 response varied from very weak in some patients to a strong reaction with proteins D2, E, G and I in others. The range of antigen-specific IgG subclass responses was similar in CF patients whose IgG fractions strongly inhibited the adherence of P. aeruginosa to epithelial cells and in those whose fractions gave only weak inhibition of adherence. There was no indication that an antibody response towards any particular OMP was implicated in the inhibition of bacterial adherence. Thus, the IgG subclass response to OMPs did not exert a significant effect on adherence when investigated in isolation, but may possibly play some role in combination with other processes.