Epitope fine specificity of human anti-HLA-A2 antibodies. Identification of four epitopes including a haptenlike epitope on HLA-A2 at lysine 127.
Anti-HLA-A2 CREG antibodies were purified from seven individuals by affinity chromatography. The binding of the purified antibodies to single or multiple amino acid variants of HLA-A2.1 was measured with an inhibition RIA. Substitutions at 10 amino acid residues in the polymorphic alpha 1 and alpha 2 domains were important for human antibody binding; eight of these have previously been shown to be important in the binding of murine anti-HLA-A2 CREG antibodies. Unlike any previously reported murine mAbs, the binding of antibodies from two individuals was eliminated by a substitution at the HLA-A2, -24, -28 shared loop amino acid residue lysine 127. Conversely, when the asparagine at residue 127 on the non-cross-reactive HLA-A3 was replaced with lysine, antibody binding was completely restored. The results further suggest that both lambda- and kappa-containing human antibodies that bind to this region may recognize lysine 127 as a haptenlike epitope. Anti-HLA-A2 antibodies that recognized a conformational epitope defined by changes at glycine 62 in the alpha 1 domain were predominated by lambda light chains whereas those that recognize an epitope defined by a loop residue at tryptophan 107 in the alpha 2 domain were predominated by kappa light chains. The data are consistent with a model of restricted epitope recognition of HLA-A2 by human B cells that is similar to, but distinct from, epitope recognition by mouse B-cell hybridomas, and may help to explain the phenomenon of public or cross-reactive idiotypes in the HLA system.
De Vito
L D
LD
Department of Surgery, University of Wisconsin-Madison 53792.
Mason
B P
BP
Jankowska-Gan
E
E
Hogan
K T
KT
Guo
J W
JW
Lutz
C T
CT
Sollinger
H W
HW
Burlingham
W J
WJ
D000818:Animals; D000906:Antibodies / Q000097:blood / Q000276:immunology*; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000032:analysis*; D015789:HLA-A2 Antigen / Q000276:immunology*; D006241:Haptens / Q000032:analysis*; D006801:Humans; D008239:Lysine; D051379:Mice; D008958:Models, Molecular; D011863:Radioimmunoassay
D000906:Antibodies; D000939:Epitopes; D015789:HLA-A2 Antigen; D006241:Haptens; D008239:Lysine