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Cold activation of serum complement in patients with chronic hepatitis C: study on activating pathway and involvement

Y Ishii1, H Shimomura, M Itoh

  • 1Department of Medicine I, Okayama University Medical School, Japan.

Acta Medica Okayama
|August 22, 2001
PubMed

Insights

Cold activation of complement (CAC) in hepatitis C patients involves the classical or lectin pathway. IgG complexes may trigger this phenomenon, impacting complement activity during cold storage.

Area of Science:

  • Immunology
  • Virology
  • Clinical Chemistry

Background:

  • Serum complement activity (CH50) can decrease upon cold storage in chronic hepatitis C patients.
  • The underlying mechanisms of this cold-induced complement alteration remain unclear.

Purpose of the Study:

  • To investigate the factors contributing to cold activation of complement (CAC) in hepatitis C.
  • To identify the complement pathway activated during CAC and the role of immunoglobulins.

Main Methods:

  • Measurement of complement cleavage products (C4d, Bb) after cold serum storage.
  • Assessment of hemolytic activity after incubation with Protein G Sepharose.
  • Fractionation of CAC-positive serum using Superose 6HR chromatography.

Main Results:

  • Significant increase in C4d levels in CAC-positive sera after cold storage, indicating classical or lectin pathway activation.
  • Bb levels did not increase, ruling out alternative pathway involvement.
  • Hemolytic activity was retained after Protein G treatment, but CAC-inducing factors were identified in specific serum fractions.

Conclusions:

  • Cold activation of complement in hepatitis C likely proceeds through the classical or lectin pathways.
  • Immunoglobulin G (IgG) complexes, potentially formed during hepatitis C virus infection, appear to be key inducers of CAC.
  • CAC may represent a common extrahepatic manifestation in hepatitis C patients.

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