The cross-reactive idiotopes recognized by the monoclonal antibodies 9G4 and LC1 are located in framework region 1 of two non-overlapping subsets of human VH4 family encoded antibodies.
The monoclonal anti-idiotopic antibodies LC1 and 9G4 bind two non-overlapping sets of VH4 encoded antibodies. 9G4 exclusively binds VH4-21 encoded antibodies, while LC1 binds antibodies derived from VH4 family gene segments V71-2, V71-4, VH4-18, VH72-1 and V2-1. The VH4-21 gene segment is utilized by most cold agglutinin (CA) antibodies with I/i specificity, while antibodies encoded by other VH4 gene segments are associated not with CA disease, but primarily with rheumatoid-factor (RF) activity. We previously determined that the idiotope to which 9G4 binds in VH4-21-derived antibodies is located in framework region 1 (FR1). In the present study, by using mutational analysis involving individual framework- and complementarity-determining region exchanges between VH4-21- and V71-2-encoded antibodies, we have found that the idiotope to which LC1 binds in V71-2-derived antibodies also maps to FR1. The LC1 idiotope is heavy (H)-chain associated, but requires pairing with a light (L) chain for LC1 binding. Recombinant antibodies composed of a variety of kappa (kappa) and lambda (lambda) L chains paired with either a V71-2 or VH4-21 chain were produced in the baculovirus expression system. LC1 bound all of the kappa-containing antibodies but did not bind the V71-2-encoded H chain alone nor to the two lambda-containing antibodies. This experiment demonstrates that not all light chains exert equivalent influence on the conformation of the H-chain idiotope. These results indicate that the FR1 of VH4-encoded antibodies is immunogenic and suggest a physiological role of FR1 during an immune response.
Department of Microbiology, University of Texas Southwestern Medical Center, Dallas 75235.
K N
KN
Potter
Y C
YC
Li
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Capra
D000595:Amino Acid Sequence; D000888:Antibodies, Anti-Idiotypic / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001483:Base Sequence; D002460:Cell Line; D003429:Cross Reactions / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005822:Genetic Vectors; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000276:immunology*; D008969:Molecular Sequence Data; D017924:Nucleopolyhedroviruses; D011994:Recombinant Proteins; D014162:Transfection
D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; D011994:Recombinant Proteins