Inducible transcription of the unrearranged kappa constant region locus is a common feature of pre-B cells and does not require DNA or protein synthesis.

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Abstract
Transcription of unrearranged .kappa. constant region (.kappa.0) loci is dramatically induced in pre-B cells transformed by the Abelson murine leukemia virus when the cells are exposed to bacterial lipopolysaccharide (LPS). Transcriptional activity, detected both by accumulation of the 8-kilobase .kappa.0 RNA product and by nuclear run-on measurements, is evident within a few hours after exposure to LPS and continues to increase over a 24-h period. During this time, transcription of rearranged .mu. H-chain loci remains at the basal constitutive level. In accord with previous studies of the B-cell lymphoma 70Z/3, this transcriptional activation is accompanied by the appearance of a DNase I-hypersensitive site in the .kappa. enhancer region but not by any detectable hypomethylation of the locus. Induction of .kappa. transcription can occur in the absence of DNA or protein synthesis. A model is proposed in which an external signal such as LPS or a functionally equivalent lymphokine may initiate .kappa. transcription in pre-B cells by modifying or overriding the activity of an enhancer-specific factor.