The influence of allotypes on the IgG subclass response to chromosomal β-lactamase of Pseudomonas aeruginosa in cystic fibrosis patients

Abstract

SUMMARY Sera from 70 adult cystic fibrosis (CF) patients with chronic lung infection with Pseudomonas aeruginosa were typed for seven GM and two KM allotype determinants. IgG class and all four IgG subclasses of antibodies against chromosomal β-lactamase of Ps. aeruginosa (aβab) were measured in all 70 CF patients in a cross-sectional study. The aβab IgG subclass response in sera collected during the first 11 years of chronic infection from 20 CF patients (10 patients with G3M*5 G1M*3/G3M*5 G1M*3 genotype and 10 patients with G3M*21 G1M*1/G3M*21 G1M*1 genotype) was analysed in a longitudinal study. Increased levels of IgG2 were associated with the presence of GM 23 allotype. IgG3 aβab levels were the lowest for subjects with the GM 1,2,3,17 23 5,21 and GM 1,3,17 21 phenotypes and the highest in subjects with GM 3,23,5 and GM 3,5. No significant differences in IgG1 and IgG4 aβab levels were found between the different phenotypes. IgG1 aβab levels were higher in patients with KM*3/KM*3 genotype compared with patients with KM*3, *1 genotype. Patients with G3M*5 G1M*3/G3M*5 G1M*3 genotype had in both the cross-sectional and the longitudinal study higher IgG3 aβab, lower IgG4 aβab levels and poorer lung function than patients with G3M*21 G1M*1/G3M*21 G1M*1 genotype. An influence of the allotypes on the clinical course of chronic lung infection with Ps. aeruginosa in patients with CF is suggested.