Effect of aspirin on complement in vivo

Area of Science:

• Immunology
• Pharmacology

Background:

• Aspirin is a widely used nonsteroidal anti-inflammatory drug.
• The complement system is a crucial part of innate immunity.
• Adverse reactions to aspirin can occur, but their mechanisms are not fully understood.

Purpose of the Study:

• To investigate the effect of a single 1g aspirin dose on complement consumption in healthy volunteers.
• To assess changes in complement activity (CH50) and specific complement components (C1, C4, C2).
• To evaluate the impact of aspirin on C1 inactivator (C1 IA) levels.

Main Methods:

• Administered 1g of aspirin to 20 healthy volunteers.
• Measured whole complement activity (CH50) before and after aspirin ingestion.
• Quantified levels of complement components C1, C4, C2, and C1 inactivator (C1 IA).

Main Results:

• Complement consumption was observed in 18 out of 20 volunteers.
• A slight to moderate decrease in CH50, C1, C4, and C2 levels was noted.
• Reduced C1 IA levels were found in 19 out of 20 volunteers.
• These changes were transient, with complement titers returning to normal levels within 30 minutes.

Conclusions:

• Aspirin ingestion transiently activates complement consumption and reduces C1 IA levels in healthy individuals.
• The observed effects are short-lived, suggesting a limited role in chronic aspirin-related adverse events.
• Further research is warranted to explore the precise role of complement in aspirin's pharmacological actions and potential adverse reactions.