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Relationships between alternative complement pathway activation, C-reactive protein, and pneumococcal infection
Journal of Clinical Microbiology
|January 1, 1986
Summary
Severe pneumococcal disease is linked to reduced alternative complement pathway (AP) factors, especially with high C-reactive protein (CRP) levels. CRP may boost AP activation as a key defense mechanism.
Area of Science:
- Immunology
- Microbiology
- Infectious Disease
Background:
- Opsonization of Streptococcus pneumoniae (PNC) without specific antibody can involve the alternative complement pathway (AP) or C-reactive protein (CRP).
- Understanding these mechanisms is crucial for managing pneumococcal disease severity.
Purpose of the Study:
- To investigate the roles of AP and CRP in pneumococcal disease pathogenesis.
- To correlate complement component levels and activation with disease severity.
Main Methods:
- Studied 19 patients with varying pneumococcal infection severity.
- Measured C4, CRP levels, and zymosan-induced 50% hemolytic complement (CH50) activity in acute and weekly sera.
- Analyzed complement consumption and its relation to PNC serotypes and CRP levels.
Main Results:
- Patients with complicated illness had significantly lower acute CH50 and zymosan-induced complement consumption compared to uncomplicated cases.
- Lower-numbered PNC serotypes correlated with reduced AP factor availability, irrespective of illness severity.
- Higher CRP levels were inversely associated with zymosan-induced complement activation in complicated illness.
Conclusions:
- In vivo depletion of AP factors is more pronounced in complicated pneumococcal illness and linked to elevated CRP.
- C-reactive protein may augment alternative pathway activation, acting as a crucial pre-antibody defense.
- These findings highlight the interplay between complement, CRP, and pneumococcal disease outcomes.