title: Total interleukin-6 in plasma measured by immunoassay.
abstract: Determinations of total cytokine concentration in biological fluids by immunoassays face two major problems: the biochemical heterogeneity of the analyte and the interference of cytokine-binding proteins. We developed an ultrasensitive enzyme immunoassay for interleukin-6 (IL-6), using monoclonal antibodies and acetylcholinesterase as the tracer enzyme. The antibodies recognized recombinant and glycosylated forms of IL-6 equally. The antibodies measured dimeric recombinant IL-6, yet we could not detect IL-6 oligomers in plasma samples. We investigated the potential interference of soluble IL-6 receptor (sIL-6R), which is present at high concentrations in plasma samples (1 to 2 nmol/L). Heat treatment of the sample obviated the sIL-6R interference. Using calibrators in a plasma matrix, we demonstrated by fractionation, dilution, and recovery experiments that the immunoassay accurately measured total IL-6 in both normal and pathological serum and plasma samples.
authors.affiliation: Immunotech S.A. 130, Marseille, France.
authors.forename: H
authors.initials: H
authors.lastname: Brailly
authors.forename: F A
authors.initials: FA
authors.lastname: Montero-Julian
authors.forename: C E
authors.initials: CE
authors.lastname: Zuber
authors.forename: S
authors.initials: S
authors.lastname: Flavetta
authors.forename: J
authors.initials: J
authors.lastname: Grassi
authors.forename: F
authors.initials: F
authors.lastname: Houssiau
authors.forename: J
authors.initials: J
authors.lastname: vanSnick
mesh_terms: D000911:Antibodies, Monoclonal; D006031:Glycosylation; D006358:Hot Temperature; D006801:Humans; D007124:Immunoenzyme Techniques / Q000706:statistics & numerical data; D015850:Interleukin-6 / Q000097:blood* / Q000737:chemistry; D046911:Macromolecular Substances; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000737:chemistry; D012680:Sensitivity and Specificity
chemical_list: D000911:Antibodies, Monoclonal; D015850:Interleukin-6; D046911:Macromolecular Substances; D011994:Recombinant Proteins