The invention relates to a method of causing an interaction of CD94/NKG2+ cells, which method comprises contacting the cells with recombinant HLA-E under binding conditions. The HLA-E property of binding to CD94/NKG2 receptors on NK cells and a subset of CD8+ T cells is useful for targeting CD94/NKG2+ cells for a variety of purposes such as identification, isolation, killing or inactivation.