The majority of human CD3 epitopes are conferred by the epsilon chain.
Transgenic mouse T cells expressing the human CD3 epsilon chain bind the majority (29/36) of monoclonal antibodies (mAbs) specific for human CD3. A proportion of these mAbs are also able to recognize isolated CD3 epsilon in a soluble, recombinant form. Thus, CD3 epsilon can confer most CD3 epitopes on the TCR--CD3 complex, but many determinants may require assembly of the complex for their formation. A number of mAbs did not recognize epsilon-transgenic T cells and probably need other CD3 subunits for binding. CD3-specific mAbs from each of the three groups defined here, as well as mAbs directed against the TCR alpha beta heterodimer, are all able to activate T cells. Therefore mAb attachment at several different sites on the TCR--CD3 complex can give rise to activation signals. This suggests that the cross-linking function of mitogenic antibodies may be their most significant property, rather than the perturbation of a particular 'functional epitope'.
Tunnacliffe
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A
Basel Institute for Immunology, Switzerland.
Olsson
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C
de la Hera
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A
D000818:Animals; D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D017252:CD3 Complex; D003432:Cross-Linking Reagents; D000939:Epitopes / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D011948:Receptors, Antigen, T-Cell / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology
D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D003432:Cross-Linking Reagents; D000939:Epitopes; D011948:Receptors, Antigen, T-Cell