A Study of QLS2404 Injection in Healthy Participants and Participants With Rheumatic Autoimmune Diseases

Inclusion Criteria: * Ia * Participants who understand and comply with the study procedures and methods, voluntarily participate in this trial, provide written informed consent, and are able to complete the study in accordance with the protocol requirements. * Male or female participants aged ≥18 and ≤45 years on the date of signing the informed consent form. * Body mass index (BMI) at screening ≥19 kg/m² and ≤26 kg/m², with body weight ≥45 kg. * Participants assessed by the investigator to be in good health based on medical history, physical examination, vital signs, and laboratory test results during the screening period. * Ib * Participants who voluntarily sign the informed consent form before the initiation of any study-related procedures, are able to communicate effectively with the investigator, understand and are willing to strictly comply with the requirements of this clinical study protocol, and complete the study. * Male or female participants aged ≥18 and ≤65 years at the time of signing the informed consent form. * Body mass index (BMI) at screening ≥18 kg/m² and ≤35 kg/m². * Participants with systemic lupus erythematosus must meet the 2019 European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria for SLE and be diagnosed with systemic lupus erythematosus; the diagnosis must have been established at least 6 months prior to signing the informed consent form. * Participants with primary Sjögren's syndrome must meet the 2016 ACR/EULAR classification criteria for primary Sjögren's syndrome and be diagnosed with primary Sjögren's syndrome; the diagnosis must have been established at least * months prior to signing the informed consent form. Exclusion Criteria: * Ia * QTcF interval corrected by electrocardiogram (ECG) ≥450 ms at screening; and any other ECG abnormalities that, in the investigator's opinion, may pose an unacceptable risk to the participant. * Participants with a history of, or current, chronic or serious diseases of the musculoskeletal, neuropsychiatric, endocrine, circulatory, respiratory, digestive, urinary, reproductive, or other systems, who are considered by the investigator to be unsuitable for participation in the clinical trial. * Participants who have lost more than 400 mL of blood due to blood donation or other reasons within 3 months prior to screening. * Participants who are considered by the investigator to be unsuitable for participation in the clinical trial or unable to complete this study for other reasons. * Ib * Any disease or condition that, in the investigator's opinion, may interfere with the evaluation of study drug efficacy, participant safety assessment, or interpretation of study results. * Participants who have participated in any cell therapy, gene therapy clinical trial, or medical device clinical trial within 3 months prior to screening. * Participants who have received Bacillus Calmette-Guérin (BCG) vaccination within 1 year prior to screening. * Participants who have received any live attenuated vaccine within 1 month prior to screening or who require live attenuated vaccination during study participation. * Participants who are breastfeeding or have a positive serum human chorionic gonadotropin (hCG) test during the screening period.