To investigate the lung expression of the three most highly weighted genes (KLRF1, LTK, VCAN) identified by our biomarker panels when comparing IPF vs non-IPF ILD (S3 Table), we used ISH on TMA sections consisting of twelve cores from five patients with IPF, ten cores from three patients with HP, and four cores from two patients with SSc-ILD (Fig 2), all of which showed no significant between-group differences in demographic or clinical variables (Table 2). This evidence concerns the gene LTK and systemic sclerosis.