CD Antigens
Product List
CD4 (26-396) Human
CD4 (26-396) Human Recombinant
CD4 (26-396) Human, Sf9
CD4 (26-396) Human Recombinant, Sf9
CD4 Human (125-202)
CD-4 (125-202 a.a.) Human Recombinant
CD4 Human (203-317)
CD-4 (203-317 a.a.) Human Recombinant
CD4 Human, Active
CD4 Human Recombinant, Active
HEK293 Cells
Introduction
CD4, or Cluster of Differentiation 4, is a glycoprotein found on the surface of immune cells such as helper T cells, monocytes, macrophages, and dendritic cells . It serves as a co-receptor for the T-cell receptor (TCR) and is a member of the immunoglobulin superfamily . CD4 is crucial for the immune system’s ability to recognize and respond to pathogens.
Key Biological Properties: CD4 is a 55 kDa type I integral membrane protein consisting of four extracellular immunoglobulin-like domains (D1 to D4), a transmembrane region, and a short cytoplasmic tail .
Expression Patterns: CD4 is primarily expressed on the surface of helper T cells (CD4+ T cells), but it is also found on monocytes, macrophages, and dendritic cells .
Tissue Distribution: CD4+ T cells are distributed throughout the body, particularly in lymphoid tissues such as the thymus, spleen, and lymph nodes .
Primary Biological Functions: CD4+ T cells play a pivotal role in the adaptive immune response. They help activate other immune cells by releasing cytokines, which are signaling molecules that modulate the immune response .
Role in Immune Responses: CD4+ T cells are essential for initiating and coordinating the immune response against pathogens. They assist in the activation of B cells to produce antibodies and the activation of cytotoxic T cells to kill infected cells .
Pathogen Recognition: CD4+ T cells recognize antigens presented by MHC class II molecules on the surface of antigen-presenting cells (APCs). This recognition is crucial for the activation of the immune response .
Mechanisms with Other Molecules and Cells: CD4 acts as a co-receptor for the TCR, enhancing its ability to recognize antigens presented by MHC class II molecules . The extracellular D1 domain of CD4 binds to the β2 region of MHC class II .
Binding Partners: CD4 interacts with MHC class II molecules on APCs, facilitating the activation of T cells .
Downstream Signaling Cascades: Upon antigen recognition, CD4+ T cells initiate a cascade of intracellular signaling events that lead to the activation and proliferation of T cells. This includes the activation of protein kinases and transcription factors that drive the expression of genes involved in the immune response .
Transcriptional Regulation: The expression of CD4 is tightly regulated at the transcriptional level. Various transcription factors, such as GATA3 and ThPOK, play a role in the differentiation and maintenance of CD4+ T cells .
Post-Translational Modifications: CD4 undergoes several post-translational modifications, including phosphorylation, which can modulate its activity and interactions with other proteins .
Biomedical Research: CD4 is widely used as a marker to identify and study helper T cells in immunological research .
Diagnostic Tools: CD4 counts are used to monitor the immune status of individuals with HIV/AIDS. A low CD4 count indicates a weakened immune system and a higher risk of opportunistic infections .
Therapeutic Strategies: Targeting CD4+ T cells is a strategy in various immunotherapies, including treatments for autoimmune diseases and cancer .
Development: CD4+ T cells develop in the thymus, where they undergo selection processes to ensure they can recognize foreign antigens while being tolerant to self-antigens .
Aging: The number and function of CD4+ T cells can decline with age, leading to a weakened immune response in elderly individuals .
Disease: CD4+ T cells are critical in the pathogenesis of several diseases, including HIV/AIDS, where the virus specifically targets and depletes these cells . They are also involved in autoimmune diseases and cancer .
