The DTA-1 monoclonal antibody specifically reacts with mouse Glucocorticoid-Induced TNFR-related protein, also known as GITR and TNFRSF18, a 66-70 kDa homodimer glycoprotein, detected in the T cells treated with glucocorticoid dexamethasone. GITR is also expressed in nave mice by CD25+/CD4+/CD8a- thymocytes and on CD25+/CD4+/CD45RB-low splenocytes. Low levels were detected in splenic CD25+/CD4+/CD45RB-low T cells, B cells, dendritic cells and macrophages. A GITR ligand was detected on dendritic cells, macrophages and B cells.The DTA-1 antibody stimulates GITR and abrogates suppression by T regulatory cells (Treg), without affecting their proliferation.

DTA-1 administration or the removal of GITR-expressing cells led to organ specific autoimmune disease.