The DTA-1 antibody reacts with mouse CD357, also known as GITR or AITR (in humans), a 66-70 kDa member of the Tumor Necrosis Factor superfamily (TNFRSF18). GITR is primarily found on T cells, and its function may vary depending on the T cell type where it is expressed. GITR is upregulated on activated T cells where it provides co-stimulation, yet GITR may promote the inhibition of CD4+ CD25+ Treg cells, where it is expressed at high levels. GITR ligand (GITRL) is found on B cells, macrophages, dendritic and endothelial cells, and is implicated in regulating both innate and adaptive immune responses.

The DTA-1 antibody may be used for analysis of GITR expression on T cells, and is also commonly used in vitro as an agonistic antibody to induce GITR signaling in various assays.