Renal Pathology

IgA Nephropathy

• common in NM
• often triggered by upper respiratory infection (sometimes GI)
• 1-3 days after infection; e.g., tonsillitis
• presents as nephritic syndrome
• most common in young adults, less so in children
• clinical course highly variable
• heal with return to normal function
• progess to renal failure
• can be treated with immune suppressants
• can be associated with systemic vasculitis =  Henoch Schonlein Purpura
• skin rash (purpura)
• pathogenesis
• IgA = antibodies of mucosal immune response
• IgA forms complexes with antigens in circulation
• IgA antibodies deposit in mesangium=incite inflammation
• IgA antibodies deposit in walls of small arteries (in Henoch Schonlein Purpura)
• histopathology - "antler guy"

Rapidly Progressive Glomerulonephritis 

• includes 3 different diseases
• post strep (post infectious) GN
• 1-4 weeks after strep/other infections
• common in children 6-10 years
• most recover completely
• pathogenesis
• formation of immune complexes
• circulate and deposit in glomerular basement membrane
• incite inflammation
• elevated antistreptolysin-O (ASO) titer in serum
• swelling of endothelial cells obstructs capillaries
• red cells pass through damaged basement membrane
• pauci immune GN = ANCA 
• anti-glomerular basement membrane GN (anti-GBM GN)