Description: The L243 mAb reacts with the human major histocompatibility complex (MHC) class II, HLA-DR. HLA-DR is expressed on the surface of human antigen presenting cells (APC) including B cells, monocytes, macrophages, DCs, and activated T cells. HLA-DR is a heterodimeric transmembrane protein composed of alpha and beta subunits and plays an important role in the presentation of peptides to CD4+ T lymphocytes. The L243 antibody recognizes a different epitope than the LN3 monoclonal antibody,and these antibodies do not cross-block binding to each other's respective epitopes.Applications Reported: This L243 antibody has been reported for use in flow cytometric analysis.Applications Tested: This L243 antibody has been pre-diluted and tested by flow cytometric analysis of normal human peripheral blood cells. This may be used at 5 µL (0.25 µg) per test. A test is defined as the amount (µg) of antibody that will stain a cell sample in a final volume of 100 µL. Cell number should be determined empirically but can range from 10^5 to 10^8 cells/test.Alexa Fluor 700 emits at 723 nm and can be excited with the red laser (633-647 nm). Most instruments will require a 685 LP mirror and 710/20 band pass filter. Please make sure that your instrument is capable of detecting this fluorochrome.Excitation: 633-647 nm; Emission: 723 nm; Laser: Red Laser

HLA-DR, like other MHC class II molecules, is a transmembrane glycoprotein composed of a 36 kDa alpha chain (DRA) and 27 kDa beta chain (DRB). The alpha chain gene contains 5 exons. Exon 1 encodes the leader peptide, exons 2 and 3 encode the two extracellular domains, and exon 4 encodes the transmembrane domain and the cytoplasmic tail. DRA does not have polymorphisms in the peptide binding part and acts as the sole alpha chain for DRB1, DRB3, DRB4 and DRB5. Within the DR molecule the beta chaincontains all the polymorphisms specifying the peptide binding specificities. Hundreds of DRB1 alleles have been described and typing for these polymorphisms is routinely done for bone marrow and kidney transplantation. HLA-DR is expressed primarily on antigen presenting cells such as B lymphocytes, monocytes, macrophages, thymic epithelial cells and activated T lymphocytes. Three loci, DR, DQ and DP, encode the major expressed products of the human class II region. The human MHC class II molecules bind intracellularly processed peptides, present them to T-helper cells, and have a critical role in the initiation of the immune response

Normal human peripheral blood cells were stained with Mouse IgG2a kappa Isotype Control, Alexa Fluor 700 (Product # 56-4724-80) (blue histogram) or HLA-DR Monoclonal Antibody, Alexa Fluor 700 (purple histogram). Cells in the lymphocyte (left) or monocyte (right) gates were used for analysis.