The CD25 antibody (clone 3G10) recognizes a 55 kDa glycoprotein also known as the low-affinity interleukin-2 receptor alpha chain (IL-2Rα). This molecule reveals three epitope regions: A, B, and C. Clone 3G10 recognizes epitope region A.
The CD25 antigen is expressed on activated T and B cells, on macrophages, and on a subset of non-activated CD4-positive regulatory T cells.