IL4 and hemophagocytic syndrome: On the other hand, HLH arises from the uncontrolled proliferation and activation of CD8 cytotoxic T cells and natural killer cells, leading to the excessive release of pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), and IL-1, IL-4, IL-6, IL-8, IL-10, IL-18 commonly referred to as a cytokine storm [37].