Orthogonal validation of RXFP1 reactivity, and correlation with AIH disease activity. (a) SLBA validation of anti-RXFP1 peptide reactivity in various patient groups (x axis), as measured by enrichment of relative light units (RLU, y axis); the cutoff for positivity was set at the mean + 3 SD of all controls (blue dashed line). (b) PhIP-seq data plotting Z-score of anti-RXFP1 peptide reactivity among AIH patients (y axis); AIH patients were separated into groups of active versus inactive AIH (x axis); patients considered as positive/reactive against anti-RXFP1 had a Z-score of enrichment >2.5 (denoted by blue dashed line, highlighted in pink).