The PathHunter CD200 Ligand cell line is a stable, engineered cell line designed for use with CD200R Checkpoint Signaling Cell Lines. When co-cultured, the CD200 expressed in this cell line will induce activity of CD200R receptors, which may be assayed through SH2 domain protein recruitment. This product is a companion product designed to work with Immunoglobulin Superfamily Checkpoint Assays. The cell line included overexpresses CD200 cell surface ligand. When co-cultured with the CD200R Checkpoint Signaling Cell Line, the CD200 ligand binds to the checkpoint receptor, inducing receptor activity. This receptor activity leads to recruitment of the relevant SH2 domain protein to the checkpoint receptor inside the receptor cell line and production of EFC signal. This stable modified cell line is provided as two vials of cryopreserved cells.