Cell surface receptor that may play a role in the innate and adaptive immune response. Acts as a counter-receptor for CD276 and interaction with CD276 on T-cells enhances T-cell activation (By similarity). Interacts with CD276 and this interaction enhances T-cell activation. Detected in B-lymphocytes and macrophages. Detected in spleen, lymph nodes, blood, bone marrow and cells from the peritoneal cavity (at protein level). Up-regulated in neutrophils and macrophages in response to bacterial lipopolysaccharide (LPS) and inflammatory stimuly.