The 2A3 monoclonal antibody specifically binds to human CD25, the low-affinity alpha subunit of the Interleukin-2 Receptor (IL- 2Rα)
CD25 associates with CD122 (IL-2Rβ chain) and CD132 (common γ chain or γc) to form the high-affinity signal-transducing IL-2R complex
CD25 is expressed by subsets of thymocytes and peripheral blood lymphocytes including CD4+CD25+ regulatory T cells and memory T cells
CD25 antigen density increases on activated T cells including phytohemagglutinin (PHA)-, concanavalin A (Con A)-, and CD3-activated T lymphocytes
High levels of CD25 can be expressed by T lymphocytes from mixed lymphocyte cultures and by human T-lymphocyte leukemia virus (HTLV)-infected T-lymphocyte leukemia lines, for example, HUT-102
CD25 can also be expressed by activated B cells and macrophages
Recombinant IL-2 blocks the binding of the 2A3 antibody to PHA-activated T lymphocytes.