To screen for LILRB3 ligands on the surface of tumour cells, we constructed 2B4 reporter cells that expressed the extracellular domains of a commonly occurring allelic variant of LILRB3 [allele LILRB3*12, (12)], or LILRB1 fused to the human CD3ζ cytoplasmic domain. Here, LILRB3 is linked to neoplasm.