Chicken CD28 antigen is a type I transmembrane monomeric glycoprotein which does not contain the cysteine residues that form disulfide-linked covalent homodimers found in the mammalian counterpart. This may reduce the avidity of binding to individual ligand molecules expected to be present on Ag presenting cells. Peripheral gamma/delta+ T cells are CD28-negative.1 Monoclonal antibodies against CD28 have a costimulatory effect on T cells stimulated by phorbol myristate acetate (PMA), concanavalin A or MAbs against the avian T cell receptor (TCR). Both Vbeta1- and Vbeta2-expressing cells respond equally well to stimulation with anti-CD28 in combination with PMA. These responses are resistant to cyclosporin A, but inhibited by herbimycin A, suggesting that CD28 employs a signalling pathway at least partly distinct from that triggered by TCR/CD3.2
Intended for research use only. Not for use in human, therapeutic, or diagnostic applications.