Induced rearrangement of k genes in the BLIN-1 human pre-B cell line correlates with germline J-C_k and V_k transcription

The human pre-B acute lymphoblastic leukemia cell line, BLIN-1, has been previously shown to undergo k light chain rearrangement in vitro, making it a valuable resource for analyzing pre-B to B cell differentiation. We have examined the recombination potential of BLIN-1 by characterizing several independently derived k-expressing subclones for DNA rearrangement and V_k gene usage. Analysis of five k-expressing subclones (all having the same heavy chain rearrangement) demonstrated independent k light chain rearrangement events by DNA hybridization analysis. Northern blot analysis using probes recognizing the four different V_k families revealed that two subclones used the most proximal V_k (V_kIV), one subclone used a V_kI, and one subclone used a V_kII. By polymerase chain reaction analyses, we detected transcripts from rearranged V-J-C_k genes as well as transcripts from germline J-C_k and V_k in BLIN-1 cells induced to rearrange the k locus. k germline transcripts were also detected in normal developing B cell populations in fetal liver and bone marrow. Our collective results indicate that: (a) BLIN-1 can be induced to rearrange the k locus, and this correlates with the expression of germline k locus transcripts that may play a role in activating or targeting gene rearrangement; and (b) active rearrangement and usage of V genes representing different k families suggest that, like in the mouse, repertoire diversification in humans occurs in the presence of a fixed heavy chain rearrangement.