When we compared the levels of the cytokines between the primary and secondary HLH groups, the IL-4 level in primary-HLH was significantly lower than that in secondary HLH (P = 0.025), with mean (95 % CI) in primary and secondary HLH groups showed as 1.1 (0.6–1.6) and 2.3 (1.9–2.7), respectively. Here, IL4 is linked to hemophagocytic syndrome.