[A member of the immunoglobulin gene super family. Co-regulator of T cell activation with CD86. Plays a critical role in autoimmune, humoral, and transplant responses. Expressed on activated T and B cells and on macrophages. (from PROW) ( NCI )] (UMLS (NCI) C0104998) =Amino Acid, Peptide, or Protein; Immunologic Factor ;