The antigen is CD25, a 55kD glycoprotein. The antibody recognizes epitope region C of the IL-2 receptor complex. Antigen distribution: Isolated cells: The antibody stains less than 5 % of resting human peripheral blood mononuclear cells in flow cytometry. Tissue sections: Scattered large and small lymphocytes in germinal centers, in follicle mantle, and T-zone. Specificity: Human: CD25 Other: not tested.