Activated human T cells express a ligand for the human B cell-associated antigen CD40 which participates in T cell-dependent activation of B lymphocytes.
To identify the ligand for the B cell-associated antigen CD40, we constructed a chimeric immunoglobulin molecule where the extracellular portion of the CD40 protein replaced the normal immunoglobulin variable region. No binding was detected on resting peripheral blood T cells. However, following T cell activation with phorbol esters and ionomycin, the chimeric protein bound specifically to activated human T cells and precipitated a 35-kDa protein from such cells. The induction of the CD40 ligand was detectable on the cell surface after 1 h, with maximal expression after 8 h of stimulation. The T cells expressing CD40 ligand were predominantly CD4 positive, although a proportion of CD8-positive cells also expressed the protein. There was no particular correlation with CD45 phenotype. Finally, we found that soluble CD40 inhibited T-dependent B cell proliferation. The results are discussed in the context of cognate interactions between B and T cells.
Lane
P
P
Basel Institute for Immunology, Switzerland.
Traunecker
A
A
Hubele
S
S
Inui
S
S
Lanzavecchia
A
A
Gray
D
D
D000328:Adult; D015703:Antigens, CD / Q000378:metabolism*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000378:metabolism*; D001402:B-Lymphocytes / Q000276:immunology*; D001483:Base Sequence; D017252:CD3 Complex / Q000502:physiology; D019013:CD40 Antigens; D006801:Humans; D066298:In Vitro Techniques; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010641:Phenotype; D011233:Precipitin Tests; D013601:T-Lymphocytes / Q000502:physiology*
D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D017252:CD3 Complex; D019013:CD40 Antigens