CD Antigens

Key Biological Properties: CD8B is an integral membrane glycoprotein that is essential for the immune response. It functions primarily as a co-receptor for MHC class I molecule:peptide complexes .

Expression Patterns: CD8B is expressed on the surface of cytotoxic T cells, natural killer cells, cortical thymocytes, and dendritic cells .

Tissue Distribution: The CD8 co-receptor is predominantly found in lymphoid tissues, including the thymus, spleen, and lymph nodes. It is also present in peripheral blood .

Primary Biological Functions: CD8B plays a critical role in the immune response by aiding in the recognition and elimination of pathogen-infected cells and tumor cells. It acts as a co-receptor with the TCR to recognize antigens presented by MHC class I molecules .

Role in Immune Responses: CD8+ T cells, which express the CD8 molecule, are essential for the adaptive immune response. They recognize and kill infected or malignant cells by releasing cytotoxic granules containing perforin and granzymes .

Pathogen Recognition: CD8B, in conjunction with the TCR, binds to MHC class I molecules presenting pathogen-derived peptides, leading to the activation and proliferation of cytotoxic T cells .

Mechanisms with Other Molecules and Cells: CD8B forms a heterodimer with the CD8 alpha chain (CD8A) to create the functional CD8 co-receptor. This heterodimer interacts with the TCR and MHC class I molecules on antigen-presenting cells (APCs) .

Binding Partners: The CD8 co-receptor binds to the alpha-3 domain of MHC class I molecules, stabilizing the interaction between the TCR and the antigen-MHC complex .

Downstream Signaling Cascades: Upon antigen recognition, the CD8 co-receptor recruits the protein tyrosine kinase Lck to the TCR complex, initiating a cascade of phosphorylation events that lead to the activation of transcription factors such as NFAT, NF-κB, and AP-1 .

Transcriptional Regulation: The expression of CD8B is regulated by various transcription factors, including T-bet and Eomes, which are critical for the development and differentiation of CD8+ T cells .

Post-Translational Modifications: CD8B undergoes post-translational modifications such as ubiquitination, which can regulate its stability and localization within the cell .

Biomedical Research: CD8B is widely used as a marker for cytotoxic T cells in immunological studies. It is also used to study T cell development, differentiation, and function .

Diagnostic Tools: Antibodies targeting CD8B are used in flow cytometry, immunohistochemistry, and other diagnostic assays to identify and quantify CD8+ T cells in various clinical samples .

Therapeutic Strategies: CD8+ T cells are being explored as therapeutic agents in adoptive cell transfer therapies for cancer and viral infections. Enhancing the function of CD8+ T cells through genetic engineering or immune checkpoint blockade is a promising strategy in immunotherapy .

Development: CD8B is crucial for the development of cytotoxic T cells in the thymus. It is involved in the positive selection of thymocytes that can recognize MHC class I molecules .

Aging and Disease: The function of CD8+ T cells can decline with age, leading to impaired immune responses. Dysregulation of CD8B expression or function is associated with various diseases, including autoimmune disorders, infections, and cancers .