Inclusion Criteria:

          -  1) the patient has suffered from multiple myeloma (according to the updated diagnostic
             criteria of IMWG)Need to meet one or more of the following: • elevated blood calcium
             (> 11.5 mg/dL) > 2.65 tendency/L, renal insufficiency (creatinine > 2 mg/dL) [177
             (including mol/L or higher] or creatinine clearance < 40 ml/min, anemia (hemoglobin <
             10 g/dL and hemoglobin below normal floor > 2 g/dL), bone disease (soluble osseous
             lesions or osteoporosis) in X-ray radiography and CT bone or PET - CT found in more
             than one place or bone lesionsOr in compliance with any of the following: • bone
             marrow clonal plasma cells greater than or equal to 60% • abnormal serum free light
             chain ratio greater than or equal to 100 (involvement) or <0.01 (involvement) • focal
             lesions of >1 found by functional imaging examination including PET/CT and/or
             whole-body MRI2) immunohistochemistry or flow cytometry detection of positive BCMA
             expression in patients with refractory recurrent multiple myeloma;Refractory
             definition: 1) at least through second-line treatment with bortezomib or lenadamine or
             2) clinician determination.Definition of recurrence: see NCCN clinical guidelines for
             multiple myeloma (2016.v2), including post-transplant recurrence.3) age: 18 to 80
             years old;4) the expected survival period is more than 3 months;5) score 0-2 for ECOG
             (refer to annex 2)6) hemoglobin (Hb) is greater than or equal to 80g/L; Neutrophil
             count absolutely (ANC) > 1 x 10 ^ 9 / L; The platelet total (PLT) 50 x 10 ^ 9 or
             higher/L.Volunteer to participate in the test and sign the informed consent

        Exclusion Criteria:

          -  1) patients with high-risk viscera involvement: tumor invading central nervous system,
             gastrointestinal tract, lung, pericardium, one of the large vessels;2) those who have
             graft versus host reaction and need to use immunosuppressive agents; Or people with
             autoimmune diseases;3) patients who used chemotherapy or radiotherapy within 3 days
             before blood sampling;4) a combination of systemic steroid use within 5 days before
             the blood collection period (except for recent or current use of inhaled steroids);5)
             use drugs to stimulate the production of bone marrow hematopoietic cells within 5 days
             before the blood collection period (such as elevating white needle);6) have used any
             gene therapy products before;7) history of epilepsy or other diseases of the central
             nervous system;8) New York heart association (NYHA) class for Ⅲ above (see attachment
             3);9) the normal upper limit of creatinine >1.5 times or ALT/AST>3 times or bilirubin
             >2 times;10) active hepatitis b or c, HIV or other uncured active infected persons;11)
             pregnant or lactating women;12) patients with other uncontrolled diseases, which are
             deemed inappropriate by researchers;Any condition that may increase the risk of the
             subject or interfere with the results of the study.