Autoimmune VH gene family: PCR-generated murine germline VH10 genes.

A relatively large number of variable region genes (V) contribute, via gene rearrangements with smaller numbers of additional gene elements (D and J), to generate diversity in the immune response. While some VH gene families are thought to contain 100- 1000 members, the VH10 family has only two known functioning members with 99% sequence homology. Both members (monoclonal antibodies) are capable of binding DNA, and since they were derived from inbred mice afflicted with the lupus syndrome they are considered autoimmune antibodies. Relative uniqueness of the VH10 primary nucleotide sequence presents a model system with which to examine unrearranged VH genes and attempt to identify germline genes eventually expressed as autoantibodies. PCR amplified germline sequences of the VH10 family are highly conserved, with few base substitutions evenly distributed between both framework and CDR regions. It was determined that the PCR amplified germline sequences are highly similar to the DNA sequences of the two monoclonal VH10 antibodies, and a non-functional psuedo-germline gene was found that is identical to a non-functional cDNA derived from a hybridoma cell line. These findings indicate that the use of unique CDR DNA sequences for the identification and amplification of specific germline V genes via PCR can yield vital information that may answer fundamental questions about the origins of autoimmune anti-DNA antibodies in afflicted individuals. The nature of the germline gene populations and the possible microheterogeniety of these genes may prove to be important in understanding the role of autoimmune antibodies in normal and diseased individuals.

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