IgG Background Staining in Diabetic Nephropathy

Immunofluorescence staining with IgG in a patient with diabetic nephropathy shows enhanced linear staining along the glomerular basement membranes and all other basement membranes. This includes the tubules and Bowman’s capsule. It also highlights the mesangial nodules. This is non-specific and not to be confused with anti-glomerular basement membrane antibody disease (anti-GBM, also called Goodpasture Syndrome). Diabetic staining is 1+ to 2+ and distributed along all basement membranes. If anti-GBM is also present in diabetic nephropathy, the IgG will be 3+ along the GBMs and the other basement membranes will have the background 1+ to 2+ staining. Sometimes this is easier said than done. (IgG 200x)