PD-1 Antibody for Reactive EBV After BMT

Inclusion Criteria: 1. 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). Chronic active EBV infection (CAEBV) was diagnosed by WHO criteria. 2. Undergo allo-HCT, have achieved full chimerism 3. Age \>18 years old, gender is not limited. 4. After transplantation, EBV was reactivated and EBV-DNA was positive in blood 5. No secondary graft failure. (After grafted, ANC \<0.5\*10\^9/l,PLT \<10\*10\^9/l) 6. No uncontrollable infection 7. Withdraw immunosuppressor, no graft-versus-host disease was observed. 8. Before the start of the study, aminopherase (ALT/AST) and total bilirubin were normal. Serum creatinine ≤ 1.5 times the upper limit of Normal (ULN); No thyroid dysfunction. The left ventricular ejection fraction (LVEF) was normal. 9. Informed consent. Exclusion Criteria: 1. Allergic to toripalimab 2. Serious immunoreaction: myocardial damage, hepatitis, pneumonia 3. Central nervous system symptoms 4. Serious mental illness; 5. Active bleeding of the internal organs 6. Pancreatitis history. Patients unable to comply during the trial and/or follow-up phase; 7. Participate in other clinical research at the same time.