Classical pathway activation during an adverse response to protamine sulphate

Area of Science:

• Immunology
• Cardiology
• Pharmacology

Background:

• Protamine sulfate is used to reverse heparin anticoagulation.
• Anaphylactoid reactions to protamine sulfate can occur, especially after intravenous administration.
• Understanding the mechanism of these reactions is crucial for patient safety.

Observation:

• A severe anaphylactoid reaction occurred in a patient receiving intravenous protamine sulfate during coronary artery catheterization.
• Complement factors C3 and C4 levels decreased significantly post-administration.
• Levels of complement C3 split products, C3c and C3d, markedly increased.

Findings:

• The study observed a rapid decrease in circulating C3 and C4 concentrations, reaching a nadir within 1.3 hours.
• Markedly elevated C3c and C3d concentrations were detected shortly after protamine sulfate exposure.
• These complement factor changes gradually normalized within approximately 6 to 22 hours.

Implications:

• These findings suggest that protamine sulfate-induced anaphylactoid reactions involve complement system activation.
• The observed changes in complement factors may serve as biomarkers for reaction severity.
• Further research into complement modulation could mitigate protamine sulfate adverse effects.