Expression of a 32-kDa ligand for the CD40 antigen on activated human T lymphocytes.
To identify the ligand(s) of the human CD40 antigen, a cDNA encoding the extracellular domain of the CD40 antigen was fused to a cDNA encoding the constant region (Fc) of human IgG1. The CD40-Fc fusion protein was able to specifically bind to CD4+ and various CD8+ T cell clones activated with immobilized anti-CD3. The 125I-labeled CD40-Fc fusion protein bound anti-CD3 activated CD4+ T cell clone (MT9) with an equilibrium dissociation constant (Kd) of 10-20 nM. The human CD40-binding protein expressed on the cell surface of activated T lymphocytes is a monomeric protein of approximately 32 kDa. Minor components of 29 kDa and 17 kDa were also detected. A small proportion of CD4+ and CD8+ blood mononuclear T cells activated by anti-CD3 expressed the CD40 ligand but its detection was best observed following depletion of B cells. Addition of B cells to purified T cells abolished the binding of CD40-Fc obtained after anti-CD3 activation.
Hermann
P
P
Schering-Plough, Laboratory for Immunological Research, Dardilly, France.
Blanchard
D
D
de Saint-Vis
B
B
Fossiez
F
F
Gaillard
C
C
Vanbervliet
B
B
Brière
F
F
Banchereau
J
J
Galizzi
J P
JP
D015703:Antigens, CD / Q000378:metabolism*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000378:metabolism*; D001402:B-Lymphocytes / Q000378:metabolism; D001483:Base Sequence; D019013:CD40 Antigens; D006801:Humans; D008024:Ligands; D008213:Lymphocyte Activation; D008211:Lymphocyte Cooperation; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D014066:Palatine Tonsil / Q000166:cytology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology*; D014162:Transfection
D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D019013:CD40 Antigens; D008024:Ligands; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins