B7 is the collective name for a family of 10 transmembrane receptor proteins embedded in the
cell membrane that perform various regulatory functions for the immune system. B7-1 (also known as CD80) and B7-2 (also known as CD86) are the most prominent and thoroughly studied. The majority of this protein family is expressed on B cells. (See Table 1 below) When B7 was first being studied in the later portion of the 20
th century, it was believed that there was only one protein that varied widely in behavior. More types of proteins within the B7 family and greater details of their roles in cellular and systemic health are being continually discovered.