Analysis of variable region genes encoding a human anti-DNA antibody of normal origin. Implications for the molecular basis of human autoimmune responses.
In order to investigate the genetic basis for natural anti-DNA immune responses, we isolated and sequenced the variable gene elements (VH and VL) encoding an anti-DNA antibody expressed by a human hybridoma of normal origin (Kim4.6) and compared these sequences with those reported for four other human anti-DNA antibodies. The Kim4.6 antibody leader and VH segments were identical in nucleotide sequence with the VH1.9III germ-line VH3 gene, and the Kim4.6VL segment showed 98% nucleotide sequence identity with a V lambda I subgroup gene expressed in a Burkitt's lymphoma. Comparative analysis of Kim4.6 and other human hybridoma anti-DNA antibodies indicated that anti-DNA immune responses are diverse in terms of VH and VL gene utilization but may exhibit a bias toward rearrangement of VH genes that are over-represented in the fetal pre-B cell repertoire. Moreover, Kim4.6 and three of four other sequenced human anti-DNA antibodies appear to use a germ-line diversity gene, DXP'1, which may represent a counterpart of the DFL16.1 segment utilized in murine responses to the hapten nitrophenyl. Taken together, our findings indicate that anti-DNA immune responses can be encoded by nonmutated VH genes and that the elements and molecular mechanisms which engender this response are essentially the same among natural and lupus-associated anti-DNA antibodies. Our data also suggest that natural autoimmune responses originate early in B cell ontogeny as is consistent with the hypothesis that autoreactivity plays a major role in shaping the normal immune repertoire.
Cairns
E
E
Department of Medicine, University of Toronto, Ontario.
Kwong
P C
PC
Misener
V
V
Ip
P
P
Bell
D A
DA
Siminovitch
K A
KA
D000595:Amino Acid Sequence; D000974:Antibodies, Antinuclear / Q000096:biosynthesis / Q000235:genetics*; D001327:Autoimmune Diseases / Q000276:immunology*; D001483:Base Sequence; D002460:Cell Line; D002648:Child; D004247:DNA / Q000276:immunology*; D005803:Genes, Immunoglobulin; D006801:Humans; D006825:Hybridomas / Q000032:analysis; D007127:Immunoglobulin Constant Regions / Q000235:genetics / Q000302:isolation & purification; D007133:Immunoglobulin Joining Region / Q000235:genetics / Q000302:isolation & purification; D007135:Immunoglobulin Variable Region / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data
D000974:Antibodies, Antinuclear; D007127:Immunoglobulin Constant Regions; D007133:Immunoglobulin Joining Region; D007135:Immunoglobulin Variable Region; D004247:DNA