CD19
CD19 (B-lymphocyte antigen CD19) is a cell surface member of the immunoglobulin superfamily that acts as a coreceptor for the B-cell antigen receptor complex on B-lymphocytes. It lowers the threshold for B-cell activation, and its expression is restricted to the B-cell lineage. Browse Assay Genie's current range of CD19 research reagents below, or read on for the biology behind the target.
CD19 functions as a coreceptor for the B-cell antigen receptor complex (BCR) on B-lymphocytes. By decreasing the threshold for activation of downstream signalling pathways, it lowers the amount of antigen needed to trigger a B-cell response. Signalling through CD19 leads to activation of phosphatidylinositol 3-kinase and mobilisation of intracellular Ca(2+) stores. CD19 forms a complex with several membrane proteins, including complement receptor type 2 (CD21) and the tetraspanin CD81, and this complex reduces the threshold for antigen-initiated B-cell activation.
The CD19 gene encodes a member of the immunoglobulin gene superfamily. The protein has two N-terminal extracellular Ig-like domains separated by a non-Ig-like domain, a hydrophobic transmembrane domain and a large C-terminal cytoplasmic domain. It is found at the cell membrane and in membrane rafts. Expression is restricted to B-cell lymphocytes: CD19 is a reliable marker for pre-B cells, but expression diminishes during terminal differentiation into antibody-secreting plasma cells. Alternative splicing results in multiple transcript variants encoding distinct isoforms. HGNC lists the gene under CD molecules, immunoglobulin-like domain-containing genes and minor histocompatibility antigens, with the previous name CD19 antigen. The mouse ortholog is Cd19.
CD19 is not required for early B-cell differentiation in the bone marrow, but it is required for normal differentiation of B-1 cells, for B-cell differentiation and proliferation in response to antigen challenge, for normal serum immunoglobulin levels and for production of high-affinity antibodies. Mutations in the CD19 gene are associated with common variable immunodeficiency 3 (CVID3), characterised by failed B-cell differentiation, hypogammaglobulinaemia, an inability to mount an antibody response and recurrent bacterial infections. CD19 is also a target of chimeric antigen receptor (CAR) T-cells used to treat lymphoblastic leukaemia.
CD19 lowers the activation threshold of the BCR complex and engages phosphatidylinositol 3-kinase and calcium mobilisation, making it central to studies of B-cell signalling.
CD19 is restricted to B cells and marks pre-B cells, then diminishes in plasma cells, so it is used to follow B-cell differentiation stages.
CD19 is a target of CAR T-cells used in the treatment of lymphoblastic leukaemia, which makes it a focus of cell-therapy research.
Mutations in CD19 are linked to common variable immunodeficiency 3, with impaired B-cell differentiation and immunoglobulin secretion.
CD19 is a coreceptor for the B-cell antigen receptor complex. It decreases the threshold for activating downstream signalling and B-cell responses to antigen, activating phosphatidylinositol 3-kinase and mobilising intracellular calcium stores. It is needed for normal antibody responses and serum immunoglobulin levels.
The UniProt name is B-lymphocyte antigen CD19, and the HGNC full name is CD19 molecule, with the previous name CD19 antigen. No other aliases are listed. Alternative splicing produces multiple transcript variants that encode distinct isoforms.
A mouse ortholog, Cd19, exists, and check the datasheet of any product for its validated reactivity. In humans, CD19 mutations are associated with common variable immunodeficiency 3, marked by hypogammaglobulinaemia and recurrent bacterial infections. CD19 is also a CAR T-cell target in lymphoblastic leukaemia.
Other CD molecules, immunoglobulin-domain proteins and immune cell markers with products at Assay Genie.
Gene and protein annotations from HGNC, NCBI Gene and UniProt P15391; product specifications from Assay Genie datasheets.