T-lymphocyte activation antigen CD28 (CD28)

T-lymphocyte activation antigen CD28 (CD28) is a cell surface receptor primarily expressed on T cells that provides essential co-stimulatory signals necessary for full T cell activation and survival[1][3][5]. Its primary physiological ligands are CD80 (B7.1) and CD86 (B7.2) on antigen-presenting cells. Engagement of CD28, together with T cell receptor (TCR) signaling, leads to T cell proliferation, cytokine production (notably interleukins such as IL-2 and IL-6), survival, and differentiation. CD28 signaling is critical for immune responses, including regulatory T cell function and immune homeostasis[1][5]. The molecule is a homodimeric glycoprotein belonging to the immunoglobulin superfamily, with unique intracellular motifs mediating signal transduction pathways. As a therapeutic target, CD28 modulation has been explored for immunosuppression (e.g., transplantation, autoimmunity) and immune activation (e.g., cancer, but with serious safety risks such as cytokine release syndrome)[1][3][5]. CD28 status is also used as an immunological biomarker in research and clinical settings.

Other names

Cluster of Differentiation 28CD28 moleculeT-cell-specific surface glycoprotein CD28

Drugs targeting CD28 can employ several mechanisms: Co-stimulatory ligand blockade (e.g., inhibiting CD80/CD86 interaction prevents T cell activation); CD28 antagonism (blocking CD28 binding impairs costimulation, reducing immune response); or CD28 agonism (activating CD28 can lead to enhanced T cell activation, but with risk of hyperactivation/"cytokine storm").