Lupus-derived human monoclonal IgM anti-DNA antibody displays monospecificity, high affinity and private idiotype specificity.
A human monoclonal IgM k anti-DNA antibody, designated 2F7, was prepared by somatic hybridization of peripheral blood lymphocytes from a lupus patient with a human-mouse heterohybridoma cell line, K6H6/B5. 2F7 was tested for its antigen binding and idiotypic specificity by direct binding and inhibition enzyme-linked immunosorbent assays. 2F7 had a high binding activity to single-stranded DNA (ssDNA) but not to double-stranded DNA. It cross-reacted with single-stranded homopolymers with pyrimidine bases and double-stranded polynucleotides containing those homopolymers, suggesting that 2F7 recognizes a conformational determinant made up of both deoxyribose-phosphate backbone and specific nucleotide base. 2F7 did not cross-react with eight structurally unrelated self-antigens. Dissociation constant (Kd) of 2F7 for sonicated ssDNA was approximately 4.5 x 10(-9) M, indicating its relatively high affinity. Idiotypic characterization with rabbit anti-idiotype raised against 2F7 suggested that 2F7 expressed an idiotype at or near its antigen-binding sites that was not detected in sera from 20 unrelated lupus patients, 10 lupus family members and 10 normal individuals. These results suggest that certain IgM class anti-DNA antibodies in human systemic lupus erythematosus may arise by antigen stimulation and not simply by polyclonal B-cell activation.
Suenaga
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Immunology Research Laboratory, St Luke's Hospital, Kansas City, MO 64111.
Abdou
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D000818:Animals; D000974:Antibodies, Antinuclear / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000915:Antibody Affinity; D000918:Antibody Specificity; D003429:Cross Reactions; D004247:DNA / Q000276:immunology; D004277:DNA, Single-Stranded / Q000276:immunology; D006801:Humans; D007130:Immunoglobulin Idiotypes / Q000032:analysis*; D007075:Immunoglobulin M / Q000276:immunology*; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D051379:Mice; D011817:Rabbits
D000974:Antibodies, Antinuclear; D000911:Antibodies, Monoclonal; D004277:DNA, Single-Stranded; D007130:Immunoglobulin Idiotypes; D007075:Immunoglobulin M; D004247:DNA