Continuing immunoglobulin heavy chain gene rearrangements in chronic myeloid leukemia with recurrent B-lymphoid blast crises after bone marrow transplantation
Kiyoi, H.; Fukutani, H.; Yamauchi, T.; Kubo, K.; Ohno, R.; Yamamori, S.; Naoe, T.
Leukemia 9(2): 265-270
1995
ISSN/ISBN: 0887-6924 PMID: 7869762 Document Number: 443427
We sequentially analyzed the immunoglobulin heavy chain variable (IgH V) region gene of leukemia cells obtained from a chronic myeloid leukemia (CML) patient who had three episodes of B-lymphoid crisis after bone marrow transplantation. Southern blot analysis using the J-H probe showed different rearranged bands at each crisis, although the same rearranged bands of the BCR gene were observed. We amplified and sequenced the IgH V region gene of the leukemia cells by reverse transcriptase polymerase chain reaction (RT-PCR) using the primers corresponding to the consensus 5'V-H and mu constant regions. The dominant leukemia clone at each crisis had a unique V-H-D-J-H rearrangement; VH4-A (V79)-DLR2-J5 (clone-1), VH4-B (DP70)-DK4-J6 (clone-2) and VH4-A (V79)-DN4-J6 (clone-3) at the first, second and third crises, respectively. Further analysis by PCR amplification using the consensus 5'V-H and clone-specific primers revealed that clone-1 underwent VH4 fwdarw VH3 replacement at the second crisis, and that clone-3 was already in existence at the first crisis, and that clone-3 was already in existence at the first crisis. Moreover, the DN4-J6 joining clone, in which the sequence was the same as that of clone-3, was identified at the first and third crises by PCR amplification using primers corresponding to the region upstream of the DN4 segment and DN4-J6 boundary of clone-3. These observations suggest that multiple clones were generated from the progenitor cells of blast crisis, which were transformed at a very early stage of B-lymphocyte ontogeny, by continuing rearrangement mechanisms of the IgH genes, and that the dominant clone at each crisis was undergoing change.