Clone REA301 recognizes the mouse CD101 antigen, a type I transmembrane glycoprotein also known as immunoglobulin superfamily member 2 (IgSF2) or V7. CD101 is expressed on monocytes, granulocytes, dendritic cells (DCs), and activated T cells. In humans CD101 inhibits the proliferative response of T cells to allogeneic cells or immobilized anti-CD3 antibody, suggesting that engagement of CD101 can antagonize TCR/CD3-mediated lymphocyte activation. Moreover, human peripheral CD8

 T cells that express CD101 and CD103 display suppressive function after activation with intraepithelial cells or placental trophoblasts. In addition to its role on T cells, triggering CD101 on human cutaneous DCs inhibits T cell proliferation via interleukin 10 (IL-10) production, suggesting that the CD101 molecule may be involved in tolerance induction. Studies in mice showed that cell surface expression of CD101 is highly correlated with functional suppressor activity within CD4

CD25

 T regulatory cells both 

 and

.