Autoantibodies in mice lacking terminal deoxynucleotidyl transferase: evidence for a role of N region addition in the polyreactivity and in the affinities of anti-DNA antibodies.
The generation of terminal deoxynucleotidyl transferase knockout mice (TdT0) has demonstrated that TdT is the only major activity involved in N region addition. This enzyme generates diversity by adding random nucleotides at the V-D-J junctions and by disrupting the formation of repetitive "homology-directed" junctions. Several studies have demonstrated that the Ig heavy chain third complementarity-determining region (H-CDR3) and the N region play a critical role: 1) in distinguishing between polyreactive and monospecific combining sites in natural and Ag-induced Abs; and 2) in the specificity and polyreactivity of natural autoantibodies (autoAbs) and in particular of anti-DNA Abs. To examine the impact of the lack of TdT on the natural autoAb repertoire in adult mice, we have stimulated TdT0 and TdT+ littermates with LPS. Serum studies demonstrate that TdT is not critical for the generation of B cells expressing autoAbs including anti-DNA Abs and rheumatoid factors. However, the generation of a large collection of hybridomas indicates that the frequencies of these cells are reduced in TdT0 mice mainly due to a lower incidence of polyreactivity; also, the lack of N region diversity seems to negatively affect the affinity of anti-DNA Abs. The physiologic relevance of these data is discussed.
Weller
S
S
Laboratory of Immunopathology, Central Hospital, University Hospitals of Strasbourg, France.
Conde
C
C
Knapp
A M
AM
Levallois
H
H
Gilfillan
S
S
Pasquali
J L
JL
Martin
T
T
D000595:Amino Acid Sequence; D000818:Animals; D000974:Antibodies, Antinuclear / Q000096:biosynthesis / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000378:metabolism; D000915:Antibody Affinity; D001323:Autoantibodies / Q000096:biosynthesis* / Q000378:metabolism / Q000502:physiology; D001483:Base Sequence; D004253:DNA Nucleotidylexotransferase / Q000172:deficiency* / Q000235:genetics* / Q000502:physiology; D006825:Hybridomas; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007135:Immunoglobulin Variable Region / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D012217:Rheumatoid Factor / Q000096:biosynthesis / Q000378:metabolism
D000974:Antibodies, Antinuclear; D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; D012217:Rheumatoid Factor; D004253:DNA Nucleotidylexotransferase