The anti-DNA-associated idiotype 8.12 is encoded by the V lambda II gene family and maps to the vicinity of L chain CDR1.

The 8.12 idiotype is an anti-DNA-associated Id present on lambda L chains that are expressed at high titers in 50% of patients with systemic lupus erythematosus. Since this Id can be present on as much as a third of a patient's anti-DNA antibodies and is found in renal glomeruli, 8.12 is thought to be a marker for a subset of pathogenic anti-DNA auto-antibodies. A molecular analysis of the 8.12 positive antibodies was designed to explore the genetic basis of this Id. Monoclonal human B cell lines were generated by transformation with EBV and lambda L chain-secreting lines were analyzed for Id expression and V region gene usage. In this panel of Ig lambda cell lines, the 8.12 idiotype is encoded exclusively by members of the V lambda II gene family. The sequences of several 8.12+ and 8.12- V lambda II genes are reported here and are used to map the 8.12 Id to the vicinity of CDR1, as well as to further characterize the large and polymorphic V lambda II gene family.