Butyrophilin-like 2 (BTNL2), is a butyrophilin family member with homology to the B7 costimulatory molecules. BTNL2 binds to a putative receptor on activated T cells and functions to have an inhibitory effect on CD4+ T cell proliferation (Nguyen et al. 2006). It may also bind to receptors on liver and vascular endothelium in mouse (Arnett et al. 2007). Polymorphisms in BTNL2 have been linked with various autoimmune and inflammatory diseases (Pathan et al. 2009, Mochida et al. 2009, Arnett & Viney 2014).