Anti-CD25 [7G7/B6]

Absolute Antibody

Anti-CD25 [7G7/B6]

9

This antibody is specific for human interleukin 2 (IL2) receptor alpha (IL2RA), which is expressed by activated T cells. IL2R alpha chains can exist as low-affinity monomers, or can non-covalently associate with IL2R beta chains to form high-affinity dime

This antibody recognises human IL2RA, as confirmed by immunofluorescence, FACS and immunoprecipitation analysis (Rubin et al, 1985). Sequential immunoprecipitations have shown that 7G7/B6 binds to the same 50-55 kD surface molecule as anti-Tac, a murine mAb specific for the human IL-2 receptor. However, 7G7/B6 does not compete with IL-2 and anti-Tac for binding to IL2R expressed by activated PBMCs, indicating that 7G7/B6 recognises a distinct epitope on IL2R. 7G7/B6, therefore, recognises a different epitope on IL-2Ralpha to the humanised anti-Tac monoclonal antibody daclizumab (Zhang et al, 2006). Equally, although 7G7/B6 binds to a different epitope on IL2 Ralpha to IL-2, and is, therefore, unable to block IL-2/IL2 Ralpha interaction, 7G7/B6 is still able to delay tumour progression and prolong survival in mouse models of adult T-cell leukaemia (ATL) (Phillips et al, 2000), likely by FcR-mediated death by FcRIII-expressing cells. Administration of 7B7/B6 radiolabelled with astatine-211 (211At-7G7/B6) to karpas299 leukaemia-bearing mice significantly increased survival, highlighting the potential therapeutic role for 211At-7G7/B6 in the treatment of patients with CD25-expressing leukaemias (Zhang et al, 2006). Indeed, 211At-7G7/B6 in combination with daclizumab induces significant long-term survival in murine models of adult T-cell leukaemia (Zhang et al, 2006). Additionally, 7G7/B6 armed with Yttrium-90 (90Y) significantly extends the survival of SUDHL-1 lymphoma-bearing mice significantly (Zhang et al, 2009), and presents another option for combination therapy with daclizumab. 7G7/B6 has been used in flow cytometric measurements of energy transfer efficiencies between FITC- and Cy3-conjugated mAbs bound to IL-2Ralpha, beta, and gamma subunits on Kit 225 K6 T cells, revealing that IL-2R subunits are preassembled on resting cells (Damjanovich et al, 1997). This antibody has also been used in an ELISA to assess serum levels of IL-2R (Uziel et al, 1994).

Flow Cytometry, ImmunoFluorescence, ImmunoPrecipitation, ELISA

Research Use Only

Monoclonal

7G7/B6

IL2RA

interleukin 2 receptor subunit alpha

CD25; IDDM10; IL-2 receptor subunit alpha; IL2R; IL-2R subunit alpha; IMD41; interleukin 2 receptor, alpha; interleukin-2 receptor subunit alpha; p55; TAC antigen; TCGFR

Mouse

IgG2a

Interleukin-2 receptor subunit alpha

Human

-20°C,2°C to 8°C

12352203