CD27/CD70 interactions regulate T dependent B cell differentiation

CD27 is a tumor necrosis factor (TNF) receptor family member whose expressi on is limited to cells of the lymphoid lineage. Constitutively expressed on T lymphocytes, it is a costimulatory molecule for a regulatory subset. Ind uced on B lymphocytes after antigenic challenge, it is a marker of memory c ells. CD70, CD27 ligand, is a TNF related trans-membrane protein induced up on activation on T and B cells. In complement of ligation of CD40, another TNF receptor family member expressed by B cells, CD27/CD70 interaction play s a key role in T dependent B cell responses and is responsible for plasma cell differentiation. B lymphocyte responses appear thus controlled by diff erent T cell subsets expressing CD154 (CD40 ligand), CD27, or CD70 (CD27 li gand).