OKT3, an anti-CD3 antibody mainly indicated for the treatment of acute organ transplant rejection, may also lead to severe CRS with increased serum levels of cytokines (e.g., TNF-α, IL-2, IL-6, and IFN-γ).54,55 Rituximab, a chimeric anti-CD20 mAb, is widely used to treat hematological malignancies, including CD20-positive diffuse large B-cell lymphoma and56 and chronic lymphocytic leukemia.57 Severe CRS has occurred in patients receiving rituximab, who had severe dyspnea, fever and blood pressure changes. The gene discussed is IL6; the disease is B-cell chronic lymphocytic leukemia.