Consistent with inflammatory activation of the monocyte/macrophage compartment, the surface expression of the immune regulatory Mer tyrosine kinase (MERTK) on circulating CD14 + monocytes cells was increased as early as day 1 in patients who developed severe/necrotizing AP compared to patients who did not (Additional file 1: Fig. S2). This evidence concerns the gene MERTK and alkaline phosphatase measurement.