The Interaction of Complement and Intrinsic Coagulation System: A Comparative Study between COVID-19 and Bacterial...

Area of Science:

• Immunology
• Hematology
• Infectious Diseases

Background:

• The complement and coagulation cascades are known to interact.
• Both severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and bacterial sepsis strongly activate these cascades.
• Understanding their interplay is crucial for managing critical illnesses.

Purpose of the Study:

• To compare complement and intrinsic coagulation pathway activation in patients with COVID-19 versus bacterial sepsis.
• To investigate the interplay between these two systems in the context of these infections.

Main Methods:

• Serum and plasma samples were collected from 25 ICU patients (11 COVID-19, 14 bacterial sepsis) at admission and during follow-up.
• Activities of coagulation factors XI and XII were measured.
• Levels of complement factors C3a and C5a were quantified.

Main Results:

• Coagulation factors XI and XII activities were elevated in both groups but showed no significant inter-group differences.
• Complement factors C3a and C5a were significantly higher in COVID-19 patients upon admission and during follow-up.
• These findings suggest a more pronounced complement activation in COVID-19.

Conclusions:

• Complement activation appears to be more significantly enhanced in COVID-19 compared to bacterial sepsis.
• The lack of significant differences in coagulation factors XI and XII suggests alternative pathways for complement activation in SARS-CoV-2 infection.