In patients with HLH, immune cells (such as T cells, NK cells and macrophages) are usually aberrantly activated, leading to over secretion of cytokines (a cytokine storm), including interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-10. Here, IL10 is linked to hemophagocytic syndrome.