Primary structures and chain dominance of anti-DNA antibodies.
Using several anti-DNA autoantibodies, we analyzed the relative involvement of heavy and light chains in their interactions with DNA. We previously obtained eight hybridomas producing monoclonal anti-DNA autoantibodies by fusing spleen cells from an MRL-lpr/lpr mouse with myeloma cells. The chain dominance was analyzed by UV cross-linking experiments, in which the antibodies were covalently cross-linked with radioisotope-labeled oligonucleotides by short-wavelength UV-light, and the cross-linked H and L chains were analyzed by SDS-PAGE and densitometric scanning. Among these, three were found to be heavy chain dominant antibodies in which heavy chains are dominantly involved in DNA binding. The other five were co-dominant antibodies in which both heavy and light chains are involved in DNA binding. To determine the factor(s) that can explain the chain dominance in DNA binding, we determined the amino acid sequences of the variable regions of both heavy (VH) and light (VL) chains of all eight monoclonal antibodies. By analyzing the data, we were able to draw the following conclusions: (1) The arginine residues are found in the CDR3 regions of both VH and VL of the co-dominant antibodies; whereas, the same residues are found only in the CDR3s of VH, but not in VL, of the heavy chain dominant antibodies. (2) The net charges of the V regions affect the chain dominance. From the results of this study it is suggested that the presence of arginine residue in CDR3 is a critical factor in determining chain-dominance, as well as DNA binding of anti-DNA antibodies in general.
Laboratory of Immunology, Institute for Medical Science, Ajou University School of Medicine, Suwon, Korea.
J S
JS
Park
Y T
YT
Kim
H Y
HY
Chung
K
K
Baek
Y J
YJ
Jang
D000595:Amino Acid Sequence; D000818:Animals; D000974:Antibodies, Antinuclear / Q000737:chemistry* / Q000235:genetics* / Q000276:immunology; D000911:Antibodies, Monoclonal; D001120:Arginine; D002459:Cell Fusion; D022801:Complementarity Determining Regions / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D003432:Cross-Linking Reagents; D017931:DNA Primers; D016056:Immunodominant Epitopes; D007135:Immunoglobulin Variable Region / Q000235:genetics; D051379:Mice; D019463:Mice, Inbred MRL lpr; D008969:Molecular Sequence Data; D009101:Multiple Myeloma; D013154:Spleen / Q000166:cytology; D014407:Tumor Cells, Cultured; D014466:Ultraviolet Rays
D000974:Antibodies, Antinuclear; D000911:Antibodies, Monoclonal; D022801:Complementarity Determining Regions; D003432:Cross-Linking Reagents; D017931:DNA Primers; D016056:Immunodominant Epitopes; D007135:Immunoglobulin Variable Region; D001120:Arginine