Membranoproliferative GN and C3 glomerulopathy
- Lesion
Glomeruli become lobular and their walls split into double contours. The cause is either immune complexes or runaway complement.
What it is
Membranoproliferative glomerulonephritis (MPGN) is a pattern of injury, not a single disease: mesangial proliferation plus capillary walls that duplicate as mesangial cells push into them. It is now divided by immunofluorescence. Immune-complex MPGN shows immunoglobulin and complement and follows chronic infections (hepatitis C with cryoglobulins, hepatitis B, endocarditis), lupus or monoclonal gammopathies. C3 glomerulopathy shows C3 with little immunoglobulin and comes from overactive alternative complement pathway; it includes dense deposit disease and C3 glomerulonephritis.
Structure
- Glomeruli are hypercellular and lobulated; mesangial cells and matrix extend into the capillary wall.
- New basement membrane forms inside the wall, so silver shows a double outline.
- Immune-complex type: subendothelial (and mesangial) deposits on EM.
- Dense deposit disease: very dense, sausage-shaped transformation of the lamina densa; C3GN: deposits that are less dense and in several sites.
Immune-complex MPGN vs C3 glomerulopathy
| Feature | Immune-complex MPGN | C3 glomerulopathy |
|---|---|---|
| Immunofluorescence | Immunoglobulin plus complement | C3 dominant, little or no immunoglobulin |
| Mechanism | Chronic antigen exposure, classical pathway | Uncontrolled alternative pathway |
| Associations | Hepatitis C, cryoglobulins, hepatitis B, lupus, endocarditis, monoclonal proteins | C3 nephritic factor, factor H or I variants; dense deposit disease with lipodystrophy |
Clinical notes
- Adolescents or young adults with combined nephritic and nephrotic features and low complement.
- Mixed cryoglobulinemia from hepatitis C gives purpura, arthralgia, neuropathy and MPGN.
- Both forms tend to progress, and C3 glomerulopathy often recurs in a transplant.
Test yourself
Think of the answer, then tap the question to see it.
What produces the tram-track appearance in MPGN?
Mesangial cells interpose into the capillary wall and new basement membrane forms, duplicating it.
Which infection is most associated with immune-complex MPGN?
Hepatitis C, usually with mixed cryoglobulinemia.
What is C3 nephritic factor?
An autoantibody that stabilizes the alternative pathway C3 convertase, so C3 is consumed continuously.
Elsewhere in DurgiPedia
Connections
Microorganisms1
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: C3 glomerulopathy: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2025); Glomerulonephritis: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2025).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.