Proportions and identity of IgA1-degrading bacteria in periodontal pockets from patients with juvenile and rapidly progressive periodontitis.

Abstract

Degradation of immunoglobulin A1 (IgAl) has previously been demonstrated in suspected periodontal pathogens. The present study revealed that a considerable proportion of the microbial flora in periodontal pockets of patients with juvenile periodontitis (median 29%) and rapidly progressive periodontitis (median 27%) was capable of degrading IgAl. Four different types of degradation occurred: Complete degradation of IgAl; extensive degradation leaving the Fc part of the molecule intact; traditional IgAl protease activity yielding intact Fc and Fab fragments, and removal of carbohydrate side chains on the IgAl molecule. Apart from species already known to degrade IgAl. IgAl protease was, for the first time, demonstrated in strains of Veillonella spp. The ability to cleave off carbohydrate side chains was a feature of a wide variety of bacteria belonging to the species Streptococcus sanguis, S. mitior, S. milleri, Veillonella spp., Actinomyces naeslundii. A. viscosus. Arachnia propionica, and Bacterionema matruchotii. The ability of subgingivally colonizing bacteria to degrade IgA may be a factor contributing to aggravation and perpetuation of the inflammatory reaction in the periodontal tissues.