Integrin alpha-6 (CD49f) defines a novel and distinct subset of CD4+ regulatory T cells with potent suppression activity.

A common method used both in vitro and in vivo, to identify Tregs in CD4+ T cells is through the characterization of surface marker CD25. Although CD25 expression is well correlated with regulatory activity in vitro, CD4+CD25+ T cells are not the only regulatory CD4+ T cells in vivo. Studies suggest that in many situations, CD4+CD25 T cells are as effective as CD4+CD25+ T cells in controlling T cell mediated disease. Therefore, CD25 is not a uniquely specific cell surface marker for the identification of Tregs. CD49f is an 6-integrin subunit which dimerizes with either the 1 or 4 subunit to form receptors for various laminin isoforms. We found that CD4+ T cells from NOD mice express CD49f, and old non-diabetic NOD mice had an increase of CD4+CD49f+ T cells in the spleen and peripheral lymph node when compared to both young and diabetic mice.

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