PD1 Antibody and Lenalidomide as a Treatment for EBV-HLH or CAEBV

Inclusion Criteria: 1. Patients with CAEBV confirmed by 2016 Revised World Health Organization classification. 2. If the patient has previously suffered CAEBV-HLH, the HLH should be in remission. 3. A woman of childbearing age must be determined not to be pregnant by a pregnancy test and is willing to take effective measures to prevent pregnancy during the trial period and ≥12 months after the last administration of the drug; All male subjects used contraceptive methods during the study period and ≥6 months after the last administration; 4. Ages Eligible for Study: 1 Year to 65 Years. 5. Sign the informed consent. Exclusion Criteria: 1. Heart function above grade II (NYHA). 2. Pregnancy or lactating Women. 3. Allergic to PD-1 antibody or lenalidomide. 4. Active bleeding of the internal organs. 5. uncontrollable infection. 6. Participate in other clinical research at the same time.