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. 1985 Feb 15;226(1):199–205. doi: 10.1042/bj2260199

Complement-subcomponent-C1-inhibitor synthesis by human monocytes.

A C Yeung Laiwah, L Jones, A O Hamilton, K Whaley
PMCID: PMC1144693  PMID: 3977865

Abstract

By using a radioimmunoassay, C1-inhibitor was found to accumulate in the supernatants of human monocyte cultures. The production of this protein was inhibited reversibly by cycloheximide. When C1-inhibitor synthesis was compared with C2 synthesis, it was found that C1-inhibitor synthesis continued, whereas synthesis of C2 appeared to cease after about 7 days in culture. Immunoprecipitation of supernatants of monocyte cultures that had been pulsed with [35S]methionine showed a specific band with an Mr of 105 000. Immunoprecipitates of the lysates revealed a band of Mr 83 000; this was thought to represent a partially or non-glycosylated precursor of C1-inhibitor. C1-inhibitor produced by the monocytes was shown, by using a haemolytic assay, to be functionally active. However, the functional activity of C1-inhibitor was reduced by only 44% in the presence of cycloheximide, whereas the concentration of this protein in cycloheximide-treated culture supernatants fell by more than 93%. This finding suggests that monocytes secrete a second molecule, which inhibits C1 activity but is distinct from classical C1-inhibitor.

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Selected References

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