Background of the antigen
Lymphocyte-activation protein 3 (LAG-3), also known as CD223, belongs to the immunoglobulin superfamily and contains 4 extracellular Ig-like domains. LAG-3 binds to HLA class-II antigens and is involved in lymphocyte activation. It is found on the cell surface of activated NK and T-lymphocytes. The sequence data, exon/intron organization, and chromosomal localization all indicate a close relationship of LAG-3 to CD4.