Cell Activation CD Proteins

Markers of T cell activation include CD69, CD71 and CD25 (also a marker for Treg cells), and HLA-DR (a marker of human T cell activation). CTLA-4 expression is also up-regulated on activated T cells, which in turn outcompetes CD28 for binding to the B7 proteins. This is a checkpoint mechanism to prevent over activation of the T cell.

In dendritic cells, the most important CD markers of activation are CD80, CD86 and CD83. CD40 is already expressed in most immature dendritic cells, although their expression intensity increases strongly, following the activation.