The antigen CD28 is one of the molecules that provide co-stimulatory signals, which are required for T cell activation. The first elucidation of the molecular structure of CD28 was discovered by the German biotech company TeGenero in 2005 ^*

Cross-linking CD28 with monoclonal antibodies can provide a potent co-stimulatory signal to T cells for the production of various interleukins (IL-2 and IL-6 in particular). Ligation of CD28 on resting T cells by the B7 ligand on antigen presenting cells (APCs) results in the induction of T helper cytokines (types one and two). ^*

The drug TGN1412, also produced by TeGenero, which unexpectedly caused multiple organ failure in trials, is a superagonist of CD28 receptors.

Unfortunately it is often ignored that the same receptors also exist on cells other than lymphocytes. CD28 has also been found to stimulate eosinophil granulocytes where its ligation with anti-CD28 leads to the release of IL-2, IL4, IL-13 and INF-γ. ^**

See also

• List of human clusters of differentiation

Cell biology | Clusters of differentiation

CD28