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     Immunohistochemistry analysis of paraffin-embedded Human liver tissue using IL-2 Receptor alpha antibody.High-pressure and temperature Sodium Citrate pH 6.0 was used for antigen retrieval.Negative control was used by secondary antibody only.    

  
  

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     Immunohistochemical analysis of paraffin-embedded Human tonsils using IL-2 Receptor alpha antibody.High-pressure and temperature Sodium Citrate pH 6.0 was used for antigen retrieval.    

  
  

The IL-2 receptor alpha chain (IL-2Rα, CD25) is a key component of the high-affinity interleukin-2 (IL-2) receptor complex, which also includes IL-2Rβ (CD122) and the common gamma chain (γc, CD132). IL-2Rα is primarily expressed on activated T cells, regulatory T cells (Tregs), and certain leukemic cells. While it lacks intrinsic signaling capacity, IL-2Rα enhances IL-2 binding affinity, enabling critical immune functions such as T cell proliferation, differentiation, and immune tolerance mediated by Tregs.

Dysregulation of IL-2Rα is implicated in autoimmune diseases, organ transplant rejection, and cancers. In autoimmunity, excessive T cell activation via IL-2 signaling drives inflammation, whereas in T cell malignancies like adult T cell leukemia/lymphoma (ATLL), CD25 overexpression promotes pathological cell survival. Therapeutic antibodies targeting IL-2Rα, such as basiliximab and daclizumab, exploit this specificity. These agents block IL-2/IL-2Rα interaction, suppressing T cell activation. Basiliximab remains widely used to prevent acute organ rejection, while daclizumab (withdrawn due to safety concerns) previously treated multiple sclerosis.

Beyond immunosuppression, anti-CD25 antibodies serve diagnostic roles. Elevated CD25 levels in serum or on cell surfaces are biomarkers for diseases like ATLL or autoimmune lymphoproliferative syndrome (ALPS). Emerging applications include antibody-drug conjugates and engineered CAR-T cells targeting CD25+ malignancies. However, challenges persist in balancing efficacy with off-target effects, particularly on Tregs, which are essential for maintaining immune homeostasis. Ongoing research aims to refine targeting strategies to improve therapeutic precision.