Structure and Molecular Properties

• CD19 is a 95 kDa transmembrane protein in the B cell receptor (BCR) complex, part of the immunoglobulin family.
• Structure includes two exterior immunoglobulin-like parts and sections for membrane and cytoplasm with multiple phosphorylated tyrosine residues upon activation.
• Acts as a vital messenger molecule for signalling pathways in the immune system.
• Design remains similar across species, underscoring its role in immune function.

Expression Pattern and Developmental Regulation

• Found mainly in B cells, considered an indicator of B-cell lineage.
• Present throughout B cell development stages, disappearing upon terminal differentiation.
• Protein expression regulated at phases of B cell growth, impacting function and fate.
• Also observed in cells, but function in these cells remains unclear.
• Analysis of expression pattern helpful for targeting therapies for B-cell related conditions.

Role in B Cell Signalling and Function

• Controls B cell reactions by influencing signal transmission and fate decisions.
• Works with BCR as a co-receptor, facilitating B cell activation upon antigen recognition.
• Forms a group with CD21 and CD81, linking the natural defence system with immune reactions by responding to complement-labeled antigens.
• Boosts BCR signalling, resulting in increased B cell growth, specialization, and antibody production.
• Preserves B cell tolerance by controlling BCR signalling intensity during maturation and aiding in the removal of self-reactive B cells.

Involvement in Disease and Pathology

• Irregular expression or function linked to autoimmune disorders and B cell cancers.
• Changes in CD19 signalling can weaken B cell tolerance, leading to autoantibody creation.
• Abnormal expression or signalling observed in B cell lymphomas and leukemias, crucial for diagnosis and treatment.
• Lack of CD19 expression may lead to immune deficiency, stressing its significance.

Therapeutic Applications and Future Perspectives

• Focus of treatment methods for B cell cancers and autoimmune disorders.
• Targeted therapies, such as CAR-T cell therapy, have shown exceptional outcomes.
• Strategies involving CD19 monoclonal antibody drug conjugates show encouraging results in clinical studies.
• Leveraging CD19's specific expression in B cells to target harmful cells while sparing other immune cells.
• Insights into CD19 biology expand strategies to cater to individuals with B cell-related conditions effectively.