BTLA

B- and T-lymphocyte attenuator is a protein that in humans is encoded by the "BTLA" gene. BTLA has also been designated as CD272 (cluster of differentiation 272).
Function.
BTLA expression is induced during activation of T cells, and BTLA remains expressed on Th1 cells but not Th2 cells. Like PD1 and CTLA4, BTLA interacts with a B7 homolog, B7H4. However, unlike PD-1 and CTLA-4, BTLA displays T-Cell inhibition via interaction with tumor necrosis family receptors (TNF-R), not just the B7 family of cell surface receptors. BTLA is a ligand for tumour necrosis factor (receptor) superfamily, member 14 (TNFRSF14), also known as herpes virus entry mediator (HVEM). BTLA-HVEM complexes negatively regulate T-cell immune responses.
Clinical significance.
BTLA activation inhibits the function of human CD8+ cancer-specific T cells.