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[Complement activation during cardiopulmonary bypass: mechanism and prevention]
Insights
Complement activation increases during cardiopulmonary bypass, indicated by rising C3a, C4a, and C5a levels. Prevention strategies should target the classical pathway and alternative pathway inhibitors.
Area of Science:
- Immunology
- Cardiovascular Surgery
Context:
- Cardiopulmonary bypass (CPB) is used in open-heart surgery.
- CPB can trigger the complement system, a part of the immune response.
- Understanding this activation is key for preventing complications.
Purpose:
- To investigate the mechanism of complement activation during CPB.
- To identify specific complement fractions involved in the process.
- To inform strategies for preventing CPB-induced complement activation.
Summary:
- Serum levels of C3, C4, and C3 activator decreased post-CPB.
- Plasma levels of C3a, C4a, and C5a significantly increased post-CPB.
- Findings suggest classical pathway activation (C4b2a) and alternative pathway dysregulation contribute to increased complement activation.
Impact:
- Identifies key complement fractions (C3a, C4a, C5a) elevated during CPB.
- Suggests CPB-induced complement activation involves both classical and alternative pathways.
- Provides etiological insights for developing preventive measures against CPB-related adverse events.
Abstract:
The mechanism of complement activation during cardiopulmonary bypass was studied for the prevention. In ten patients undergoing open-heart procedures, the serum levels of complement fractions (C3, C4, and C3 activator) were measured by a single radial immune diffusion method. In four of ten patients, the plasma levels of C3a, C4a, and C5a fractions were studied by the radioimmunoassay 2 antibodies method. The serum levels of C3, C4, and C3 activator decreased after cardiopulmonary bypass. The plasma levels of C3a, C4a, and C5a increased after bypass. The lower level of C3 activator shows that C3 activator was not excessively produced during cardiopulmonary bypass. Therefore it can be thought that much C4b2a from classical pathway as well as C3a over-production localizing extra-corporeal circuits and little inhibitors on alternative pathway resulted in increased complement activation. The prevention should be done from these etiologies.