A human monoclonal antibody reacting against HLA-DQ1-, DQ4-, and a subset of DQ7-bearing cells.
Human mAb 2A2 recognizes an epitope present in the HLA-DQ1 + 4 specifications and also on several DQ7-positive cells. We have investigated the extra reactions of this monoclonal reagent on a wider panel of DQ1-, DQ4-negative/DQ7-positive B-cell lines. The results obtained support the existence of two subtypes of the HLA-DQ7 specificity on the basis of their reactivity with human mAb 2A2; the DQ7/2A2-positive variant has been found in 12 of 29 BCLs positive for the DR11 antigen, and in four of eight BCLs bearing DR4-DQ7 haplotypes. It has also been detected in the DR12-positive cells assayed and in several unusual DR/DQ7 combinations not commonly found in Caucasoid populations, including the DR13-DwHAG and DR14-Dw16 haplotypes. Results from competition binding assays between 2A2 and well-characterized murine anti-DQ polymorphic mAbs suggest that the epitope recognized by human mAb 2A2 on DQ1- or DQ4-bearing haplotypes is located on the DQ beta chains of such specificities, being amino acid residues 54-55, the potential binding site of antibody 2A2, whereas the binding site on DQ7 antigens cannot be explained on the basis of known amino acid sequences.
Sánchez
B
B
Immunology Center, Virgin of Rocío University Hospital, Andaluz de Salud Center, Seville, Spain.
de la Calle
O
O
Yélamos
J
J
Aguilera
I
I
Sánchez
F
F
Dessi
V
V
Siervo
S
S
García-Lozano
J R
JR
Melero
J
J
Magariño
R
R
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000937:Antigen-Antibody Reactions; D001402:B-Lymphocytes / Q000276:immunology*; D001667:Binding, Competitive / Q000276:immunology; D002460:Cell Line; D002472:Cell Transformation, Viral; D000939:Epitopes / Q000276:immunology; D005455:Fluorescent Antibody Technique; D006683:HLA-DQ Antigens / Q000276:immunology*; D006684:HLA-DR Antigens / Q000276:immunology; D004854:Herpesvirus 4, Human; D006801:Humans; D008969:Molecular Sequence Data; D012150:Polymorphism, Restriction Fragment Length; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D000939:Epitopes; D006683:HLA-DQ Antigens; C051568:HLA-DQ1 antigen; C060029:HLA-DQ4 antigen; C069546:HLA-DQ7 antigen; D006684:HLA-DR Antigens