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

Yasushi Ishii, Hiroyuki Shimomura, Mamoru Itoh, Masanobu Miyake, Fusao Ikeda, Jiro Miyaike, Shin Ichi Fujioka, Yoshiaki Iwasaki, Hideyuki Tsuji, Takao Tsuji

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

It has been documented that the serum complement activities measured by hemolytic assay (CH50) are decreased after storage of sera at a low temperature in some patients with chronic hepatitis C. However, the mechanism of this phenomenon has not been identified yet. Here, we tried to elucidate factors involved in the cold activation of complement (CAC). To clarify what pathway is activated in CAC, we measured complement cleavage products after cold storage of sera. C4d increased significantly after 12 h-storage at cold temperatures in 5 CAC (+) sera compared with 5 CAC (-) (P < 0.01) and 3 control sera (P < 0.05), while Bb did not increase in any of the groups. In order to determine whether IgG or IgG complex is necessary for CAC, 8 CAC (+) sera were incubated with Protein G Sepharose gel beads, and all of them retained hemolytic activities to some extent after cold storage. Column chromatography through Superose 6HR of CAC-positive serum identified the fractions containing molecules that induced CAC in normal serum, which were depleted by treatment with protein G Sepharose. In conclusion, CAC in hepatitis C seems to occur via a classical or lectin pathway, and the IgG complex produced in hepatitis C virus infection may be an important factor in inducing CAC, a common extrahepatic manifestation of hepatitis C.

Original languageEnglish
Pages (from-to)229-235
Number of pages7
JournalActa medica Okayama
Volume55
Issue number4
Publication statusPublished - Dec 1 2001

Keywords

  • Chronic hepatitis
  • Complement activation
  • Hepatitis C virus

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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