This is a single center, double-blinded, placebo-controlled phase I clinical trail in healthy volunteer of meplazumab for injection. The primary objective of this phase I trial is to evaluate the safety, tolerability, pharmacokinetic characteristics and occupancy characteristics of peripheral blood cell receptors of meplazumab in healthy volunteer, and provide a reference for the dosage of meplazumab in phase II clinical trial.

Inclusion Criteria:

• 18≤age≤50 years, males or females;
• body weight ≥50 kg, body mass index (BMI) should be within 19.0 and 24.0 (both ends included),
• Vital signs, physical examination, laboratory examination (blood routine, urine routine, blood biochemical, coagulation, etc.) and electrocardiogram are within the normal range, or beyond the normal range, but the researchers determined that the abnormality has no clinical significance (NCS).
• No bad habits, including tobacco addiction (>5 cigarettes per day) or drink addiction (>15 g of alcohol in a day, and more than two days a week for female, or >25 g in a day, and more than two days a week for male; 15 g of alcohol is equivalent to 450 mL beer, 150 mL wine or 50 mL light liquor), no history of drug abuse (defined as the use of illegal drugs);
• No birth plan during the study and within 6 months of completing the test and are willing to use non-hormonal contraceptive measures;
• Have the ability to communicate normally with medical staff and comply with relevant hospital management regulations;
• Understand the study and be willing to participate in the study, and sign an informed consent form. Incompetent subjects, willing and able to comply with all trial requirements.

Exclusion Criteria:

• History of allergies to drugs, food, protein or specific allergies (asthma, rubella, eczema dermatitis, etc.);
• Vital signs, physical examination, routine laboratory tests (blood routine, urine routine, blood biochemistry, coagulation, etc.), 12-lead ECG and other abnormalities and clinical significance;
• Positive for SARS-CoV-2 specific IgM and IgG antibodies test;
• Fever within 3 days before medication (body temperature ≥38.0 ℃);
• Pregnant or lactating women;
• Have received or are participating in other clinical trials within 3 months before the screening;
• Be diagnosed or suspected to have immunodeficiency or autoimmune diseases; undergo immunosuppressive therapy such as anticancer chemotherapy or radiotherapy before the trial, or have received systemic corticosteroid treatment within the past 6 months;
• With a history of acupuncture syncope reaction;
• Positive for HBV surface antigen, anti-HCV antibody, anti-HIV antibody, and syphilis antibody test;
• Tobacco addiction (>5 cigarettes per day) or drink addiction (>15 g of alcohol in a day, and more than two days a week for female, or >25 g in a day, and more than two days a week for male; 15 g of alcohol is equivalent to 450 mL beer, 150 mL wine or 50 mL light liquor), or can not stop smoking and drinking during the study;
• Participated in blood donation or blood loss ≥400mL within 3 months before screening;
• Patients not suitable to participate in this study by the judgment of the investigator.