Immunoassay for functional human soluble interleukin-6 receptor in plasma based on ligand/receptor interactions.
Soluble forms of most cytokine receptors, able to bind effectively to their respective ligands, have now been described. A soluble interleukin-6-binding molecule derived from the gp80 component of the multichain IL-6 receptor can be detected in biological fluids, and can act as an agonist of IL-6 activity. The clinical significance of the soluble receptor levels still remains to be explored. We took advantage of the characterization of an anti-IL-6 monoclonal antibody and of an anti-IL-6R monoclonal antibody that both bound to IL-6/IL-6R complexes to design an immunometric assay for the measurement of soluble IL-6R complexed to IL-6. This reaction scheme was designated as ELIA (enzyme-ligand immunoassay). When exogeneous IL-6 was added in excess to an sIL-6R containing sample, all sIL-6R was present in a complexed form. Thus, the reaction scheme could also be used to determine total sIL-6R concentrations. A recombinant sIL-6R standard was prepared from the supernatant of murine thymoma cells transfected with a gene coding for an extracellular portion of the IL-6 receptor. The assay permitted the precise and reproducible measurement of sIL-6R in serum or plasma. This approach is of general relevance for the determination of soluble cytokine receptors in biological fluids, provided that adequate anti-cytokine and anti-receptor antibodies are available.
Montero-Julian
F A
FA
Immunotech S.A., Marseille, France.
Liautard
J
J
Flavetta
S
S
Romagné
F
F
Gaillard
J P
JP
Brochier
J
J
Klein
B
B
Brailly
H
H
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001483:Base Sequence; D017931:DNA Primers / Q000737:chemistry; D006801:Humans; D007124:Immunoenzyme Techniques; D015850:Interleukin-6 / Q000276:immunology*; D008024:Ligands; D051379:Mice; D008807:Mice, Inbred BALB C; D008811:Mice, Inbred DBA; D008969:Molecular Sequence Data; D018123:Receptors, Interleukin / Q000032:analysis*; D019947:Receptors, Interleukin-6; D011994:Recombinant Proteins / Q000276:immunology; D015203:Reproducibility of Results; D012995:Solubility; D014162:Transfection; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D017931:DNA Primers; D015850:Interleukin-6; D008024:Ligands; D018123:Receptors, Interleukin; D019947:Receptors, Interleukin-6; D011994:Recombinant Proteins