INSERM U1223 1 article published in JoVE Immunology and Infection Development and Validation of an Ultrasensitive Single Molecule Array Digital Enzyme-linked Immunosorbent Assay for Human Interferon-α Alba Llibre*1,2, Vincent Bondet*1,2, Mathieu P. Rodero3, David Hunt4, Yanick J. Crow3,5, Darragh Duffy1,2 1Immunobiology of Dendritic Cells, Institut Pasteur, 2INSERM U1223, 3Laboratory of Neurogenetics and Neuroinflammation, INSERM UMR1163, Institut Imagine, 4MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, 5Manchester Centre for Genomic Medicine, University of Manchester Here we present a protocol to describe the development and validation of a single molecule array digital ELISA assay, which enables the ultra-sensitive detection of all IFN-α subtypes in human samples.