T-cell surface antigen CD28 (CD28)

T-cell surface antigen CD28 is a disulfide-linked homodimeric glycoprotein expressed mainly on T cells, functioning as an essential co-stimulatory receptor that binds to the B7 family ligands (CD80/CD86) on antigen-presenting cells. This interaction is necessary for full T cell activation, proliferation, cytokine production, and survival, in synergy with TCR (T-cell receptor) signaling. CD28-mediated signaling plays a pivotal role in the immune response, bridging innate and adaptive immunity and regulating the threshold for T cell activation. CD28 is a therapeutic target in autoimmune diseases, transplantation, and cancer; however, interventions must balance efficacy with risk of over-suppression or over-activation of T cells, as illustrated by past safety incidents involving superagonist antibodies[2][4][5].

Other names

Cluster of Differentiation 28T-cell antigen CD28T-cell-specific surface glycoprotein CD28

Blocking CD28-ligand interaction: Prevents co-stimulatory signaling necessary for T cell activation (e.g., Abatacept, Belatacept). Superagonistic antibodies: Hyperactivate T cells independent of TCR signal, leading to massive cytokine release (has caused cytokine storm in clinical trials). Conventional agonist antibodies: Mimic B7 ligand and require simultaneous TCR engagement for activation.