• Patients who meet the diagnostic criteria of EBV-HLH or CAEBV are confirmed to be mainly infected with B lymphocytes after the detection of EBV lymphocyte subsets. EBV-HLH diagnostic criteria: Meet hemophagocytic lymphohistiocytosis (HLH)-04 diagnostic criteria; EBV-DNA in peripheral blood or EBER in tissue were positive, patients were diagnosed with EBV associated HLH (EBV-HLH).CAEBV diagnostic criteria: (1) persistent or recurrent infectious mononucleosis-like symptoms persisting for more than 3 months; (2) EBV-DNA quantitative increase in peripheral blood or tissue lesions; (3) exclusion of other possible Diagnosis, such as primary Epstein-Barr virus infection (infectious mononucleosis), autoimmune disease, congenital immunodeficiency, human immunodeficiency virus (HIV) infection, or other underlying conditions requiring immunosuppressive therapy or underlying immunosuppression

• Before the start of the study, total bilirubin ≤10 times the upper limit of normal, serum creatinine ≤1.5 times the normal value; fibrinogen can be corrected to ≥0.6g/L after infusion.

• Serum HIV antigen or antibody negative.

• HCV antibody negative, or HCV antibody positive, but HCV RNA negative.

• HBV surface antigen and HBV core antibody are both negative. If any of the above is positive, peripheral blood hepatitis B virus DNA titer detection is required, and the number of copies less than 1×103 copies/ml can be included in the group.

• LVEF ≥ 50% by cardiac echocardiography.

• Women of childbearing age must be confirmed by a pregnancy test that they are not pregnant, and are willing to take effective contraceptive measures during the test period and within ≥ 12 months after the last dose. Women during pregnancy and lactation cannot participate. Contraceptive measures should be taken during the test period and within ≥3 months after the last dose.

• Informed consent obtained. -