CXCL9 and macrophage activation syndrome: Cytopenias (lymphopenia, thrombocytopenia) distinguished MIS-C from KD and the degree of hyperferritinemia (significantly higher in MAS compared with MIS-C) and the pattern of cytokine production (IL-18, CXCL9 and soluble IL-2 receptor levels are greatly increased in MAS) differs MIS-C from MAS [26].