Complement pathway activity in serum from patients with classical dengue fever.

Area of Science:

• Immunology
• Virology
• Infectious Diseases

Background:

• Dengue fever is a significant global health concern.
• The role of the complement system in dengue pathogenesis is not fully understood.

Purpose of the Study:

• To investigate complement pathway activity in patients with classical dengue fever.
• To determine the timing and potential triggers of complement activation during dengue infection.

Main Methods:

• Measurement of haemolytic activity to assess classical complement pathway activity (CCPA).
• Quantification of complement components C3 and C4.
• Assessment of circulating immune complexes (CIC) levels.

Main Results:

• CCPA and C4 levels were significantly decreased in 9 out of 16 patients after day 4 of fever.
• Alternative complement pathway activity remained unaffected.
• Persistent decreases in CCPA and C4, along with decreased C3 and elevated CIC, were observed in 3 patients during the convalescent stage.

Conclusions:

• Complement activation in dengue fever appears to occur later in the viraemic phase, not typically within the first 3 days.
• Circulating immune complexes may contribute to complement activation, but other unidentified factors could also play a role in some cases.