Butyrophilins (Btns) and butyrophilin-like (Btnl) molecules are emerging as novel regulators of immune responses in mice and humans. Several Butyrophilin (BTN) and Btn-like (BTNL) molecules control T lymphocyte responses, and are genetically associated with inflammatory disorders and cancer. Butyrophilin-like 3 (BTNL3) is a member of the BTN/MOG Ig-superfamily which is coded by the BTNL3 gene, also known as COLF4100 .