Treatment of Presymptomatic (Stage 1) Type 1 Diabetes Pediatric Patients With Treg Cell Preparations and Anti-CD20 Antibody

The main purpose of the study is to check: * Can therapy with a preparation of regulatory cells (Tregs lymphocytes) and/or an anti-CD20 antibody preparation (rituximab) be successfully used in children with pre-diabetes to treat or delay type 1 diabetes? * Is therapy with a preparation of regulatory cells (Tregs lymphocytes) and/or a preparation of antiCD20 antibodies (rituximab) safe for children with pre-diabetes, and what side effects may be associated with it? The study will include patients at high risk for type 1 diabetes whose laboratory tests have confirmed preserved normal/high insulin production. First (part 1 of the study), tests will be performed to determine the risk of the disease (determination of autoantibodies that characterize the autoimmune background). In order to confirm the effectiveness of the therapy, not all patients will receive the study treatment. The study will be a so-called blinded randomized trial. This means that in this trial, all participants will undergo the same study procedures, but the participant will be randomly assigned to one of four (4) groups that will receive different treatment regimens before entering the study. The participant will be randomly assigned to one of four groups: * Group I will receive a preparation of regulatory cells (Tregs lymphocytes) along with a preparation of antiCD20 antibodies, * Group II will receive a preparation of regulatory cells (Tregs lymphocytes) together with an inert substance (placebo) * Group III will receive a preparation of antiCD20 antibodies along with a sham treatment (inert substance) * Group IV will receive an agent containing an inert substance and sham treatment. Approximately 150 patients aged 6-16 who are at risk of developing type 1 diabetes will be enrolled in the study, which will last up to 96 months. Each enrolled participant will remain in the study for up to five years.