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Complement and meningococcal infection
Insights
Low serum C3 levels in meningococcal disease patients indicate complement activation, potentially causing circulatory collapse and death. Transient C3 drops also suggest immune complex formation linked to allergic complications.
Area of Science:
- Immunology
- Infectious Diseases
- Complement System
Background:
- Meningococcal disease is a serious infection.
- The role of the complement system in meningococcal disease pathogenesis is not fully understood.
Purpose of the Study:
- To investigate serum C3 levels in patients with meningococcal disease.
- To explore the association between C3 levels and disease severity, complications, and outcomes.
Main Methods:
- Serum C3 levels were measured in 211 patients with meningococcal disease.
- Complement pathways (classical and alternative) were assessed.
- Serial C3 measurements were performed in a subset of patients.
Main Results:
- Low C3 levels were observed in 13 patients with acute meningococcaemia, correlating with circulatory collapse and mortality.
- Complement activation, involving both classical and alternative pathways, was indicated.
- Patients with meningitis had higher mean C3 levels than controls.
- A transient fall in C3 was noted in 8/13 patients who developed arthritis or cutaneous vasculitis, suggesting immune complex formation.
Conclusions:
- Complement activation, particularly involving C3, plays a significant role in the pathogenesis of severe meningococcal disease.
- Low C3 levels are associated with poor outcomes, including circulatory collapse and death.
- Transient C3 depletion may indicate immune complex-mediated complications like arthritis and vasculitis.
Abstract:
Serum C3 levels were measured in 211 patients with meningococcal disease. Low levels were found in 13 patients with acute meningococcaemia, and complement activation may have contributed to the peripheral circulatory collapse that was responsible for nine deaths. The complement profile of these patients suggested activation of both classical and alternative complement pathways. Patients with meningitis had a higher mean serum C3 level than controls. Serial studies in 13 serum antigen-positive patients with meningitis who subsequently developed arthritis or cutaneous vasculitis showed a transient fall in serum C3 in eight. This fall was probably due to the formation of immune complexes that were responsible for their allergic complications.