[IgA and IgG antibodies to Chlamydia in IgA nephropathy as well as in mesangiocapillary and membranous glomerulonephritis].

It might be supposed that, among the antigens causing chronic immune complex glomerulonephritis (IC GN), there are foreign materials, e.g. bacterial antigens penetrating the mucosal barrier. To put this hypothesis to the test, the presence and titres of IgA and IgG antibodies against Chlamydia (C., one of the most frequent bacteria causing mucosal inflammation) have been studied in the sera of 70 patients with IgA nephropathy (IgA NP), of 25 with mesangiocapillary GN (MCGN) and of 27 with membranous GN (MGN) using a single serovar (L2) inclusion immunoperoxidase assay. Significantly more IgA (titres greater than or equal to 8) and IgG (titres greater than or equal to 32) antibodies were found in the sera of IgA NP and MCGN patients than in healthy controls. These results are compatible with the hypothesis that there are some similarities between the clinical and morphological picture of IgA NP and MCGN. Furthermore, it may be assumed that in renal patients with an active C. infection (high IgG titres with IgA seropositivity) C. antigens may play a role in the production of nephropathogenic IC developing in antibody excess.