Cluster of Differentiation (CD) markers constitute a system of cell surface antigens that help characterize different immune cell types based on their expression patterns. They therefore play an important role in immunology, providing insights into cell identity and function within the immune system. Each CD marker is assigned a unique number used to designate specific cell types, differentiation stages, or functional properties. CD markers are often identified using monoclonal antibodies that bind to the respective antigens. CD markers allow researchers and clinicians to identify and distinguish different cell types within the immune system. For example, CD4 is a marker for helper T cells, while CD8 is a marker for cytotoxic T cells. Many CD markers indicate specific stages of cell development or maturation. For instance, CD34 is expressed on hematopoietic stem cells, CD3 is found on mature T cells, and CD19 is present on B cells. CD markers also often correlate with specific functional properties of immune cells. For example, CD25 is associated with regulatory T cells (Tregs), which play a role in immune suppression. CD markers can also indicate whether a cell is activated or in a memory state. CD69, for instance, is a member of the C-type lectin family and is expressed on various immune cells, including T cells, B cells, natural killer (NK) cells, and certain myeloid cells. The primary function of CD69 is to modulate and regulate immune cell activation and trafficking. CD69 is rapidly upregulated on the surface of immune cells upon activation by various stimuli, such as antigen recognition, cytokines, and other immune signals. Its expression occurs early in the activation process, making it an important marker for detecting recently activated immune cells such as T cells. CD markers are also involved in cell-cell interactions and signalling. For example, CD28 on T cells provides a co-stimulatory signal that enhances T cell activation. CD28 engagement by its ligands, B7-1 (CD80) and B7-2 (CD86) on the APCs, provides the necessary co-stimulatory signals that helps amplify the T cell's response. Finally, some important examples of other CD markers are: 1) CD3, expressed on mature T cells and a key component of the T cell receptor (TCR) complex involved in antigen recognition; 2) CD4, expressed on helper T cells, which plays a central role in controlling immune responses by interacting with MHC class II molecules on APCs; 3) CD8, expressed on cytotoxic T cells, and involved in recognizing antigens presented by MHC class I molecules on infected or abnormal cells; 4) CD19, expressed on B cells and a marker for B cell development and activation; 5) CD25, a subunit of the IL-2 receptor, and associated with Tregs and other activated T cells; 6) CD56, expressed on natural killer (NK) cells and some T cells and involved in cell adhesion and cytotoxicity; 7) CD68, expressed on macrophages and used to identify tissue-resident macrophages and their activated forms; 8) CD83, a marker for mature dendritic cells (DCs) and involved in immune modulation and T cell activation. We provide a large product catalogue of research tools for investigating CD markers, including CD45 antibodies, CD10 antibodies, CD34 antibodies, ICAM1 ELISA Kits, and CD26 ELISA Kits. Explore our full CD markers product range below and discover more, for less. Alternatively, you can explore our Non Lineage, Adhesion, and Myeloid Cells product ranges.