CD244, also known as natural killer cell receptor 2B4 isoform 1, is a natural killer and T cell immunoglobulin superfamily surface protein and ligand of CD48. It is a cell surface glycoprotein related to CD2 and implicated in the regulation of natural killer and T lymphocyte function. It is expressed on all human NK cells, a subpopulation of T cells, basophils and monocytes. It activates NK cell mediated cytotoxicity, induces secretion of IFN-gamma and matrix metalloproteinases, and NK cell invasiveness. Recombinant human CD244, fused to hIgG-His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.