Human CD28 is an important costimulatory molecule found on all CD4+ T cells and on about half of the CD8+T cells. T cell activities attributed to CD28 include prevention of anergy, induction of cytokine gene transcription, stabilization of cytokine mRNAs and activation of CD8+ cytotoxic T lymphocytes. The ligands for CD28 identified as CD80 (B7-1) and CD86 (B7-2), are immunoglobulin superfamily monomeric transmembrane glycoprotein of 60 kd and 80 kd, respectively. Monovalency of the CD28 receptor for its natural ligands is essential to provide costimulation without inducing responses in the absense of TCR engagement (5)
Molecular Structure: A soluble fusion protein consisting of the mature extracellular (134aa) domain of human CD28: nkilvkqspmlvaydnavnlsckysynlfsrefraslhkgldsavevcvvygnysqqlqvysktgfncdgklgnesvtfylqnlyvnqtdiyfckievmypppyldneksngtiihvkgkhlcpsplfpgpskp
fused to murine IgG2a Fc + hinge (233aa): eprgptikpcppckcpapnllggpsvfifppkikdvlmislspivtcvvvdvseddpdvqiswfvnnvevhtaqtqthredynstlrvvsalpiqhqdwmsgkefkckvnnkdlpapiertiskpkgsvrapqvyvlpppeeemtkkqvtltcmvtdfmpediyvewtnngktelnykntepvldsdgsyfmysklrvekknwvernsyscsvvheglhnhhttksfsrtpg
predicted (non glycosylated ) monomeric molecular weight: 41.8 kd
predicted extinction coeficient: 1.13 OD for a 1mg/ml solution
Transfectant Cell Line: CHO
Functional Application: Recombinant human CD28 -muIg fusion protein blocks binding of anti-human CD28 to human tumor cells. In combination with IFN-gamma, CD28-muIg can stimulate dendritic cells in when a crosslinking agent is included (6).
1. M.K. Jenkins & J.G. Johnson, (1993) Curr Opin Immunol 5: 361-367.
2. 61st Forum in Immunology, (1995) Res Immunol 146: 127-205.
3. I. Kariv, A. Truneh & R.W. Sweet, (1996) J Immunol 157: 29-38.
4. R.J. Peach, Linsley P.S., et al. J Biol Chem (1995) 270(36): 21181-21187.