Antibodies that neutralize interleukin-17A (IL-17A) are classically detected and quantified using cell-based assays. However, these assays are cumbersome, inherently variable and often susceptible to interference by the matrix of test samples, such as human sera. Since neutralizing antibodies block binding of IL-17A to its cell surface receptor, IL-17R, we used antibody inhibition of IL-17A binding to recombinant IL-17R/Fc fusion protein in an electrochemiluminescence (ECL) platform to develop a novel, non-cell based ligand binding assay that functionally mimics cell-based neutralization assays. Using specific polyclonal antisera and a panel of sera containing neutralizing anti-IL-17A autoantibodies from patients with autoimmune polyendocrinopathy syndrome-1, we have shown that this assay generates neutralizing titers that correlate well with those found using cell-based assays. The assay is simple to perform, reliable, and more accessible to clinical laboratories than cell-based assays. In principle, the assay methodology could be extended to detection of neutralizing antibodies to biotherapeutics for assessment of unwanted immunogenicity of biotherapeutic products.
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