A conformational epitope expressed upon association of CD3-epsilon with either CD3-delta or CD3-gamma is the main target for recognition by anti-CD3 monoclonal antibodies.
We have performed immunofluorescence analysis of COS cells transfected with human CD3 genes and detergent permeabilized to define the specificity of several anti-CD3 antibodies. We have found that the mAb OKT3, WT31, UCHT1, and Leu-4 did not stain COS cells singly transfected with the CD3-epsilon chain. However, these antibodies very strongly stained COS cells doubly transfected with a combination of CD3-epsilon plus either CD3-gamma or CD3-delta. By contrast, the antibodies SP34 and APA 1/1, which were raised against isolated SDS-denatured CD3-epsilon protein, gave a strong staining of COS cells singly transfected with CD3-epsilon as well as of the double transfectans. The recognition by this panel of anti-CD3 antibodies of CD3-gamma/epsilon and CD3-delta/epsilon complexes and not of CD3-epsilon alone was assessed by immunoprecipitation. These findings suggest that the most widely used mAb specific for the CD3 complex recognize conformational epitopes on CD3-epsilon, which are expressed when this chain is bound to either CD3-gamma or CD3-delta. It should also be highlighted that antibody WT31 clearly recognizes the CD3 moiety of the TCR/CD3 complex.
Salmerón
A
A
Centro de Biología Molecular CSIC, Universidad Autónoma de Madrid, Spain.
Sánchez-Madrid
F
F
Ursa
M A
MA
Fresno
M
M
Alarcón
B
B
D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D015703:Antigens, CD / Q000276:immunology*; D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology*; D017252:CD3 Complex; D000939:Epitopes; D005455:Fluorescent Antibody Technique; D006801:Humans; D046911:Macromolecular Substances; D011233:Precipitin Tests; D011487:Protein Conformation; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D000939:Epitopes; D046911:Macromolecular Substances; D011948:Receptors, Antigen, T-Cell; D011994:Recombinant Proteins