CD Antigens

Key Biological Properties: CD74 is a non-polymorphic protein that exists in different isoforms, including p31 and p41 . It has a short N-terminal cytoplasmic tail, a transmembrane region, and a luminal domain .

Expression Patterns: CD74 is expressed on the surface of antigen-presenting cells (APCs) such as B cells, dendritic cells, and macrophages . It is also found intracellularly in various cell types .

Tissue Distribution: CD74 is widely distributed in immune-related tissues, including the spleen, thymus, and lymph nodes . It is also present in non-immune tissues such as the liver and lungs .

Primary Biological Functions: CD74 functions as a chaperone for MHC class II molecules, facilitating their proper folding and transport to the cell surface . It also acts as a receptor for macrophage migration inhibitory factor (MIF), playing a role in immune responses and inflammation .

Role in Immune Responses: CD74 is crucial for the presentation of exogenous antigens to CD4+ T cells, thereby initiating adaptive immune responses . It also regulates the development and function of T cells, B cells, and dendritic cells .

Pathogen Recognition: CD74 is involved in the recognition and processing of pathogen-derived antigens, aiding in the activation of the immune system .

Mechanisms with Other Molecules and Cells: CD74 interacts with MHC class II molecules to form a complex that is transported to the cell surface . It also binds to MIF, triggering downstream signaling pathways .

Binding Partners: CD74 forms complexes with CD44 and other cell surface receptors, influencing cell migration and survival .

Downstream Signaling Cascades: Upon binding to MIF, CD74 activates signaling pathways such as the extracellular signal-regulated kinase (ERK) pathway, the PI3K-Akt pathway, and the NF-κB pathway . These pathways regulate various cellular processes, including proliferation, survival, and inflammation .

Transcriptional Regulation: The expression of CD74 is regulated at the transcriptional level by various transcription factors and cytokines .

Post-Translational Modifications: CD74 undergoes post-translational modifications such as phosphorylation and glycosylation, which influence its stability and function .

Biomedical Research: CD74 is used as a marker for studying antigen presentation and immune cell function . It is also a target for investigating the mechanisms of immune-related diseases .

Diagnostic Tools: CD74 expression levels can be used as a diagnostic marker for certain cancers and autoimmune diseases .

Therapeutic Strategies: Targeting CD74 with specific antibodies or small molecules is being explored as a therapeutic approach for treating cancers, inflammatory diseases, and autoimmune disorders .

Development: CD74 is essential for the development of the immune system, particularly in the maturation of T cells and B cells .

Aging: The expression and function of CD74 may change with age, potentially influencing immune responses in older individuals .

Disease: Dysregulation of CD74 is associated with various diseases, including cancers, autoimmune diseases, and chronic inflammatory conditions .