Recombinant Human CD28 protein

CD28 recombinant protein is a biologically engineered molecule designed to mimic the natural CD28 receptor, a critical co-stimulatory signal transducer in T-cell activation. CD28. a member of the immunoglobulin superfamily, is expressed on the surface of T lymphocytes and interacts with B7 family ligands (CD80/CD86) on antigen-presenting cells (APCs). This interaction provides the "second signal" required for full T-cell activation, proliferation, and survival, working synergistically with the primary signal from T-cell receptor (TCR)-MHC-peptide engagement.

Recombinant CD28 proteins are typically produced using mammalian expression systems (e.g., HEK293 or CHO cells) to ensure proper post-translational modifications and structural fidelity. These proteins often include the extracellular domain of CD28. which retains ligand-binding capacity, and may be fused with Fc tags or other molecular handles for purification and functional studies. In research, CD28 recombinant proteins are widely used to investigate T-cell signaling mechanisms, immune synapse formation, and tolerance regulation. They also serve as tools for developing immunotherapies, particularly in cancer and autoimmune diseases. For example, CD28 agonists/antagonists are explored to modulate immune responses – either enhancing anti-tumor activity or suppressing pathological inflammation.

Notably, CD28 co-stimulation has therapeutic implications in chimeric antigen receptor (CAR) T-cell engineering, where its cytoplasmic domain is incorporated to improve T-cell persistence. However, recombinant CD28 proteins must be carefully characterized due to potential cross-reactivity with related receptors like CTLA-4. Current applications extend to diagnostic assays, drug screening platforms, and nanoscale immune-engineering approaches aiming to fine-tune adaptive immunity.