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Occurrence of C3 nephritic factor and C4 nephritic factor in membranoproliferative glomerulonephritis (MPGN)
1Department of Internal Medicine II, Nihon University School of Medicine, Tokyo, Japan.
Insights
Patients with hypocomplementaemic MPGN and both C3NeF and C4NeF factors show severe complement depletion and poor outcomes. These findings highlight MPGN
Area of Science:
- Nephrology
- Immunology
- Complement System
Background:
- Hypocomplementaemic membranoproliferative glomerulonephritis (MPGN) is a kidney disease characterized by low complement levels.
- The role of nephritic factors, such as C3NeF and C4NeF, in MPGN pathogenesis is not fully understood.
Purpose of the Study:
- To investigate the prevalence and impact of C3 nephritic factor (C3NeF) and C4 nephritic factor (C4NeF) in patients with hypocomplementaemic MPGN.
- To correlate the presence of these factors with clinical outcomes and complement levels.
Main Methods:
- Studied 100 patients with hypocomplementaemic MPGN (C3 < 40%).
- Assessed for C3NeF and C4NeF.
- Measured complement component levels (C3, C5, C6-C9).
- Performed immunofluorescence for immunoglobulin deposits.
- Analyzed clinical outcomes, including nephritic syndrome and prognosis.
Main Results:
- 10 patients tested positive for both C3NeF and C4NeF.
- Patients with both factors showed marked decreases in C3, C5, and late complement components (C6-C9).
- These patients exhibited persistent hypocomplementaemia post-therapy and heavy C3 immunoglobulin deposits.
- Patients with both C3NeF and C4NeF had higher rates of nephritic syndrome and poorer prognosis compared to those with only one factor.
Conclusions:
- The presence of both C3NeF and C4NeF in hypocomplementaemic MPGN is associated with severe complement activation and adverse clinical outcomes.
- These findings suggest a strong correlation between specific nephritic factor profiles, complement dysregulation, and disease prognosis in MPGN.
- Further research into MPGN as an autoimmune condition is warranted.
Abstract:
One hundred patients diagnosed with hypocomplementaemic MPGN (C3 < 40%) were studied to determine the presence of C3 nephritic factor (C3NeF) and/or C4 nephritic factor (C4NeF). Of those studied, 12 were C3NeF-positive, nine were C4NeF-positive and 10 were positive for both C3NeF and C4NeF. In the 10 patients both C3NeF- and C4NeF-positive, a marked decrease in C3 and C5 levels and a decrease in levels of late components from C6 to C9 were observed. This observation was in contrast to that seen in patients who were either C3NeF- or C4NeF-positive. Patients positive for both C3NeF and C4NeF continued to exhibit hypocomplementaemia after therapy. Immunofluorescent findings revealed heavy C3 immunoglobulin deposits in the 10 patients who were both C3NeF- and C4NeF-positive, whereas no such deposits were found in those patients who were either C3NeF- or C4NeF-positive only. When those patients who were both C3NeF- and C4NeF-positive were compared with those who were either C3NeF- or C4NeF-positive, nephritic syndrome and a poor prognosis were observed more frequently. This study demonstrates a correlation between clinical outcome and hypocomplementaemic MPGN. Further investigations of MPGN as an autoimmune disease are necessary.