Understanding the biology of the CTLA-4 pathway

Abstract

Cytotoxic T lymphocyte antigen (CTLA-4), ubiquitously expressed on activated and regulatory T-cells, is an important regulator of T-cell stimulation and proliferation that functions in opposition to CD28. CD28 is deprived of stimulus by CTLA-4 modulating its interactions with its ligands, CD80 and CD86, in a process termed trans-endocytosis (TE). This results in CTLA-4 physically removing CD80 and CD86 from antigen-presenting cells. CD80 and CD86 are transmembrane glycoproteins that are mostly interchangeably defined and predominantly expressed on antigen-presenting cells.