Preparation and characterization of MAbs against different epitopes of CD226 (PTA1)

Recently the platelet and T-cell activation antigen 1 (PTA1) was assigned a s CD226 at the 7th Conference and Workshop on Human Leukocyte Differentiati on antigens (HLDA). PTA1 is mainly expressed on activated T cells, natural killer (NK) cells, platelets and stimulated endotheliocytes, and involved i n the differentiation of cytotoxic T lymphocytes (CTL) and NK, as well as p latelet activation and aggregation. We raised hybridomas secreting monoclon al antibodies (MAbs) to PTA1 by using the natural PTA1 as immunogen, which was purified from platelets via affinity chromatography. These MAbs, design ated FMU1, FMU2, FMU3, FMU4, FMU5, FMU6 and FMU7, could recognize PTA1 cDNA transfected COS7 cells detected by flow cytometry (FCM), and also react wi th both natural PTA1 and PTA1/Ig fusion protein in indirect enzyme-linked i mmunoadsorbent assay (ELISA). The biosensor epitope mapping assay showed th at the seven MAbs, together with previous PTA1-specific MAbs Leo A1 and New E1, could bind seven distinct epitopes of PTA1, respectively. The panel of MAbs might be new powerful tools to study the structure-function relations hip of PTA1 molecule, and to search for the ligand of PTA1.