Calprotectin, a heterodimer of the two calcium-binding proteins S100A8 and S100A9 (synonyms are calgranulin A and B or myeloid related protein [MRP]-8 and MRP-14), is a major cytosolic protein in monocytes and neutrophils, secreted during infections, malignancy, and inflammation [5, 6]. Here, S100A9 is linked to infection.