Infection of Haemophilus parainfluenzae in tonsils is associated with IgA nephropathy.

We investigated the functions of tonsillar mononuclear cells (TMC) regarding whether a Haemophilus parainfluenzae (HP) outer membranes antigen (HPOM) enhances IgA-related cytokine (IFN-gamma, IL-10. and TGF-beta) production in vitro by TMC in IgA nephropathy (IgAN) patients. In addition, we examined the effect of synthetic oligodeoxynucleotide and HPOM stimulation by TMC on IgA production, whether the constant region antisense to IgA inhibits the production of IgA in vitro by TMC. Eighteen patients with IgAN and 25 patients with chronic tonsillitis (CT) from 6 to 45 years (mean age of 20.9 years) participated in this study. TMC were obtained from resected tonsils, and total and HP-specific IgA levels, along with the concentration of TGF-beta, IL-10 and IFN-gamma in the supernatant of stimulated TMC were measured by ELISA. Isolated TMC were cultured with HPOM in the presence of 23 oligodeoxynucleotides (ODNs), and the induction of total IgA and HP-specific IgA in the supernatant was also measured using ELISA. To investigate the inhibition of IgA production, TMC were cultured with HPOM and antisence to IgA. We found that IgA-related cytokine (IFN-gamma, IL-10, and TGF-beta) production by unstimulated or stimulated TMC was higher in IgAN patients than CT patients. Two types of synthetic oligodeoxynucleotides produced higher HP-specific IgA than with HPOM stimulation alone. HPOM and antisence IgA inhibited the production of total IgA and HP-specific IgA in dose-depend manner. In conclusion, IFN-gamma, TGF-beta, and IL-10 influence each other in the pathogenesis of IgAN, and infection by not only HP but other bacteria or viruses which possess specific DNA sequences such as CpG motifs induce the production of HP-specific IgA by TMC.