IL5 and hemophagocytic syndrome: First, compared with the control group, the GATA3-knockdown PTCL cells had lower levels of TH2-associated cytokines (IL4, IL5, and IL13) and VEGFA. IL-4 and IL-13 are inflammatory cytokines and may elicit or aggravate the “cytokine storm,” leading to hemophagocytic syndrome in the bone marrow and elevated serum ferritin levels.