[Study on the swine glomerulopathy resembling human IgA nephropathy]

Naturally occurring swine glomerulopathy was investigated and its glomerular tissue injury was compared with that of human IgA nephropathy. Mild proteinuria (30%) and microhematuria (17%) was found in 30 six-month-old swine. Serum creatinine level was 1.8 +/- 0.4 (mean +/- SD) mg/dl. Light microscopy (LM) disclosed diffuse or focal glomerulopathy with mesangial enlargement and hemispherical deposits in six-month-old swine. Electron microscopy revealed dense deposits in the mesangial, para-mesangial and sub-endothelium areas. On immunofluorescence+ (IF) staining findings, granular deposits of IgA (97%), IgG (97%), IgM (80%), C3 (100%), and mycoplasma hyorhinis (MH) antigen (90%) were found in the mesangial areas and along the capillary walls. One three-month-old pig and one five-year-old Goettingen mini pig were also found to have granular deposits of immunoglobulin and MH antigen in the glomerulus. In contrast, no glomerular lesion was found in all 4 new-born pigs and 4 fetal pigs by LM and IF study. In six-month-old swine anti-nuclear factor and anti-DNA antibody were negative, and no pathological lesion was found in the liver by LM. And IgA and MH antigen containing circling immune complexes were positive in sera by Raji cell assay, and moreover IgA and MH antigen was found co-depositing by the double stain techniques. These findings suggest that swine glomerulopathy is similar in appearance to human IgA nephropathy and MH antigen may contribute to the development of this nephropathy.