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     Black line: Control Antigen (100 ng);Purple line: Antigen (10ng); Blue line: Antigen (50 ng); Red line:Antigen (100 ng)    

  
  

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     Flow cytometric analysis of Jurkat cells using CD4 mouse mAb (green) and negative control (red).    

  
  

CD4 antibodies are essential tools in immunology, primarily targeting the CD4 glycoprotein expressed on the surface of helper T cells, regulatory T cells, monocytes, macrophages, and dendritic cells. The CD4 molecule serves as a co-receptor for the T-cell receptor (TCR), stabilizing interactions between TCRs and major histocompatibility complex class II (MHC II) molecules on antigen-presenting cells. This interaction is critical for T-cell activation and adaptive immune responses.

Monoclonal CD4 antibodies, such as OKT4 and Leu-3a, are widely used in research and diagnostics to identify and isolate CD4+ T cells. These antibodies bind to distinct epitopes on the CD4 extracellular domain. Some CD4 antibodies act as agonists, inducing T-cell signaling, while others block CD4-MHC II interactions, suppressing immune activation. This dual functionality makes them valuable for studying immune regulation and developing therapies.

Clinically, CD4 antibodies have therapeutic potential. Anti-CD4 monoclonal antibodies like ibalizumab are approved for HIV treatment, blocking viral entry by targeting the CD4 receptor. In autoimmune diseases, CD4-targeted therapies aim to modulate pathogenic T-cell activity. However, prolonged CD4 blockade may risk immunosuppression, necessitating careful dosing.

CD4 antibodies also play roles in cancer immunotherapy, either by depleting regulatory T cells to enhance anti-tumor responses or by engineering bispecific antibodies to redirect T cells against tumors. Their versatility underscores their importance in both basic research and translational medicine.