Independent rearrangement of Ig lambda genes in tissue culture-derived murine B cell lines.

Rearrangement of the lambda light chain locus is considered a late event in pre-B cell differentiation which occurs after successful heavy chain and unsuccessful kappa light chain rearrangement. However, this view has recently been challenged by the observation of apparently independent lambda rearrangement in certain B cell lines and Ig transgenic populations. In this study we have examined the pattern of Ig rearrangements and expression in several tissue culture-derived murine B cell lines. One pre-B cell line (BDL-1) displayed germline heavy and kappa light chain genes despite the presence of a productive lambda 1 light chain rearrangement. Two other cell lines (DAC-2, BDL-2) had multiple lambda rearrangements despite the presence of productive kappa chain rearrangements. These cell lines provide new precedents for rearrangement of the lambda locus independent of the kappa locus. Their phenotype suggests that accessibility at the different Ig loci may be controlled by a non-sequential mechanism.