The role of the immunoglobulin heavy chain in human anti-DNA antibody binding specificity.
OBJECTIVE
To investigate the structural basis for DNA binding of the natural human IgM lambda monoclonal antibody KIM4.6.


METHODS
An IgM lambda, non-DNA-reactive variant hybridoma was derived during in vitro subcloning of the anti-DNA antibody KIM4.6. The variable (V)-region heavy (H) and light (L) chain genes expressed by the variant hybridoma were amplified by polymerase chain reaction, cloned, sequenced, and compared with those of the KIM4.6 parent and other DNA-binding and non-DNA-binding antibodies.


RESULTS
The VL chain of the variant was identical to that of KIM4.6. In contrast, the VH chain was completely different from the VH chain of the parent but was similar or identical, except in the diversity (D) and joining regions, to the VH chain of the systemic lupus erythematosus (SLE) IgG anti-DNA antibody T14 and SLE IgM nephritogenic anti-DNA antibodies NE-1 and NE-13.


CONCLUSIONS
The expression of the KIM4.6 VL chain is not sufficient for DNA specificity. The VH chain and its D region play a key role in conferring DNA binding of the KIM4.6 anti-DNA antibody.
Mahmoudi
M
M
University of Western Ontario, London, Canada.
Denomme
G A
GA
Edwards
J Y
JY
Bell
D A
DA
Cairns
E
E
D000595:Amino Acid Sequence; D000974:Antibodies, Antinuclear / Q000235:genetics / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000276:immunology; D000918:Antibody Specificity / Q000276:immunology*; D001483:Base Sequence; D001666:Binding Sites, Antibody; D002999:Clone Cells; D004247:DNA / Q000276:immunology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007143:Immunoglobulin Heavy Chains / Q000737:chemistry / Q000276:immunology*; D007147:Immunoglobulin Light Chains / Q000737:chemistry / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction
D000974:Antibodies, Antinuclear; D000911:Antibodies, Monoclonal; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D007075:Immunoglobulin M; D004247:DNA