Immune Checkpoints of the B7 Family. Part 2. Representatives of the B7 Family B7-H3, B7-H4, B7-H5, B7-H6, B7-H7, and ILDR2 and Their Receptors

Abstract

Immune checkpoints regulate polarity, strength, and termination of the immune response. The leading roles in these processes are played by molecules of the B7 family. Based on data obtained using first representatives of the B7 family molecules, a two-signal model for T cells activation was proposed. The discovery of new homologues of B7-1 and B7-2 molecules revealed not only a great variety of their structural organization, but also new functions, for example the B7-H6 molecule is able to activate NK cells through interaction with NKp30 molecule. Manipulations of the B7 ligands and their interactions with specific receptors provide opportunities for fine tuning of the immune response against various pathogens and development of new drugs. The second part of this review provides information on recently discovered representatives of the B7 family, such as B7-H3, B7-H4, B7-H5, B7-H6, B7-H7, ILDR2, and their receptors.