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Restriction fragment length polymorphisms and single germline coding region sequence in VH18/2, a duplicated gene
D B Rubinstein1, M Symann, A K Stewart
1Division of Hematology/Oncology, New England Medical Center, Boston, MA 02111.
Molecular Immunology
|March 1, 1993
Summary
Gene duplication of VH18/2, a heavy chain gene for anti-DNA antibodies, explains its overrepresentation in the immune repertoire. This finding provides insights into immune system regulation and autoantibody development.
Area of Science:
- Immunology
- Genetics
- Molecular Biology
Background:
- The VH18/2 gene encodes the heavy chain of anti-DNA antibodies.
- VH18/2 is known to be overrepresented in the expressed immune repertoire with minimal divergence from its germline sequence.
Purpose of the Study:
- To analyze restriction fragment length polymorphisms (RFLPs) of the VH18/2 gene.
- To correlate VH18/2 RFLPs with its germline sequence.
- To investigate the genetic basis for VH18/2 overrepresentation and its role in the immune repertoire.
Main Methods:
- Hybridization of oligonucleotide probes to XbaI-digested genomic DNA.
- Analysis of polymorphic bands (26, 24, and 18 kb).
- Cloning and sequencing of size-selected genomic DNA containing the VH18/2 gene.
Main Results:
- Individuals exhibited one, two, or three polymorphic bands, indicating VH18/2 gene duplication at two sites within the IgH locus.
- The 26 kb and 24 kb fragments were most common, found in 97% of individuals.
- Sequencing revealed a single germline coding region sequence for VH18/2.
Conclusions:
- VH18/2 gene duplication is a likely cause of its overexpression.
- VH18/2 may play a crucial role in establishing or regulating the immune repertoire, similar to conserved autoantibody genes.