Anti-HLA-E Purified Monoclonal Antibody

HLA-E (human leukocyte antigen E) is a non-classical MHC I antigen, which is important for dialogue with NK cells and their regulation through interaction with CD94/NKG2 receptor. Like other MHC I molecules, transmembrane HLA-E molecule (45 kDa) associates with beta2 microglobulin. Unlike HLA-G, expression of HLA-E molecules is not so restricted, but it has been detected at least at mRNA level in virtually all cells and tissues examined. In peripheral blood, HLA-E protein is expressed at least in all mononuclear cells, but in different quantity (B cells and monocytes more than T cells and NK cells) .

Recombinant human HLA-E denaturated heavy chain. The antibody MEM-E/02 specifically reacts with an extracellular epitope on denaturated heavy chain of human HLA-E. HLA-E belongs to the MHC Class I molecules (MHC Class Ib; nonclassical) and it is expressed on the surface of all human cell types.

Expressed in extravillous trophoblast cells and secretory endometrial cells during pregnancy (at protein level) . The expression in nonlymphoid tissues is restricted to endothelial cells from all types of vessels, including arteries, veins, capillaries, and lymphatics (at protein level) . In lymphoid organs, it is mainly expressed in endothelial venules, B and T cells, monocytes, macrophages, NK cells and megakaryocytes (at protein level) .

Immunohistochemistry (paraffin sections) : 5-10 μg/ml; positive control: human placenta; heat antigen retrieval (sodium citrate), incubation with mAb: 1 hour / RT, detection DAB.

Non-classical major histocompatibility class Ib molecule involved in immune self-nonself discrimination. In complex with B2M/beta-2-microglobulin binds nonamer self-peptides derived from the signal sequence of classical MHC class Ia molecules (VL9 peptides) (PubMed:9754572, PubMed:18083576, PubMed:18339401) . Peptide-bound HLA-E-B2M heterotrimeric complex primarily functions as a ligand for natural killer (NK) cell inhibitory receptor KLRD1-KLRC1, enabling NK cells to monitor the expression of other MHC class I molecules in healthy cells and to tolerate self (PubMed:9754572, PubMed:9486650, PubMed:17179229, PubMed:18083576) . Upon cellular stress, preferentially binds signal sequence-derived peptides from stress-induced chaperones and is no longer recognized by NK cell inhibitory receptor KLRD1- KLRC1, resulting in impaired protection from NK cells (PubMed:12461076) . Binds signal sequence-derived peptides from non-classical MHC class Ib HLA-G molecules and acts as a ligand for NK cell activating receptor KLRD1-KLRC2, likely playing a role in the generation and effector functions of adaptive NK cells and in maternal-fetal tolerance during pregnancy (PubMed:9754572, PubMed:30134159) . Besides self-peptides, can also bind and present pathogen-derived peptides conformationally similar to VL9 peptides to alpha-beta T cell receptor (TCR) on unconventional CD8+ cytotoxic T cells, ultimately triggering antimicrobial immune response (PubMed:16474394, PubMed:30087334) .