This is a single center, randomized, double-blind, placebo-controlled, single and multiple dose escalation phase 1 study. The objective of this study is to evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of subcutaneous administered SHR-1819 in healthy subjects

Inclusion Criteria:

1. Ability to understand the trial procedures and possible adverse events, volunteers to participate in the trial, and provides written informed consent.
2. Be able to comply with all the requirements and able to complete the study.
3. Male or female aged between 18 years and 55 years (inclusive) at the date of signed consent form.
4. No clinically significant abnormalities in medical history, general physical examination, vital signs, and laboratory tests.
5. Men and women of childbearing potential (WOCBP) must agree to take effective contraceptive methods and have no plan to have a child from signing the consent form to 16 weeks after IP administration.

Exclusion Criteria:

1. Positive hepatitis B virus (HBsAg), hepatitis C virus (HCV-Ab), human immunodeficiency virus (HIV-Ab), or QuantiFERON-TB Gold tests at screening;
2. Participation in clinical trials of other investigational drugs or medical devices within 3 months prior to screening (according to the date of signed consent form), or in the follow-up period of a clinical study
3. Severe injuries or surgeries within 6 months before screening or plan to do surgeries during the trial
4. Any other circumstances that, in the investigator's judgment, may increase the risk associated with the subject's participation in and completion of the study or could preclude the evaluation of the subject's response