huCD19(2) Mouse

The CD19 gene encodes a member of the immunoglobulin gene superfamily. As a key co-receptor in the B cell receptor (BCR) signaling pathway, it is crucial for B cell development, activation, and differentiation. CD19, a pan-B-cell marker exclusively expressed in the B cell lineage, remains stable throughout B cell development, from pro-B cells to mature and memory B cells. It acts as a positive regulator of BCR signal transduction by forming a B cell-specific signaling complex with CD21 (complement receptor 2), CD81 (tetraspanin), and CD225 (Leu13), which lowers the threshold for antigen-induced B cell activation ^[1]. Dysregulation of CD19 is strongly linked to autoimmune diseases such as systemic lupus erythematosus (SLE) and B cell malignancies like acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphoma. Mutations in this gene are associated with common variable immunodeficiency 3 (CVID3), characterized by impaired B cell differentiation and hypogammaglobulinemia. Owing to its B cell-specific expression, CD19 has become a pivotal target for immunotherapy. For example, anti-CD19 CAR-T cell therapy (e.g., Tisagenlecleucel) has shown remarkable efficacy in refractory or relapsed ALL ^[2]. Recent studies have also explored CD19-targeted bispecific antibodies (e.g., blinatumomab) to enhance tumor cell clearance ^[3].

The huCD19(2) mouse is a humanized model generated using gene editing technology by replacing the sequence from the start codon to the stop codon in the endogenous murine Cd19 gene with the corresponding sequence of human CD19. This model is applicable for studying B cell development and function, as well as therapeutic research on autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), and B cell malignancies. It is an ideal research platform for preclinical efficacy evaluation of anti-human CD19 CAR-T cell therapy and the development of bispecific antibodies and combination therapies.