HBA2 and alkaline phosphatase measurement: Most importantly, expanding a nine‐gene transcriptome signature (S100A8, DUSP1, JUN, HBA2, FOS, CYBA, JUNB, S100A9, and WDR83OS) obtained from B cells to whole immune cells from the PBMCs, the AUROC values remained high across internal and external validation cohorts for predicting AP complications (albeit reduced AUROC for external validation) and persistent organ failure.