An ATL cell line with an IgH pseudo-rearranged band pattern by southern blotting: a pitfall of genetic diagnosis.
Adult T-cell leukemia (ATL), which is a mature T-cell malignancy that develops from human T-cell leukemia virus type-1 (HTLV-1)-infected T-cells, is diagnosed based on morphologic, immunophenotypic, serologic, and genetic characteristics. In particular, Southern blot hybridization (SBH) and polymerase chain reaction analyses for antigen receptor genes and the retrovirus of HTLV-1 provide a diagnostic hallmark for the clonality of leukemic cells and the causative agent of the disease. We report here a case of an ATL cell line, designated as SO4 cells, established from primary ATL cells presenting with an irrational genetic abnormality of the immunoglobulin heavy chain (IgH)-rearranged band in spite of harboring a clonally rearranged T-cell receptor gene and a clonally integrated provirus of HTLV-1 within their genomic DNA. Moreover, fluorescence in situ hybridization analysis using the IgH (14q32) dual-color break-apart probe revealed 3 pair-signals of colocalizing red and green spots, implying 2 intact and 1 amplified 14q32 regions without translocation, where the region contains the IgH gene locus. Although the exact mechanism remains to be elucidated, some alteration of a portion of the amplified 14q32 region seems to have a role in the false-positive band pattern in the SBH. The SO4 cells, in the hematology laboratory, will provide a lesson about the pitfalls of genetic tests for mature T-cell neoplasms and contribute to the genetic elucidation of leukomogenesis as an in vitro model.
Uemura
Akiko
A
Department of Laboratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
Sugahara
Kazuyuki
K
Nagai
Hiroshi
H
Murata
Kenn
K
Hasegawa
Hiroo
H
Hirakata
Yoichi
Y
Tsukasaki
Kunihiro
K
Yamada
Yasuaki
Y
Kamihira
Shimeru
S
D000328:Adult; D015139:Blotting, Southern / Q000379:methods; D002460:Cell Line; D002874:Chromosome Mapping; D002883:Chromosomes, Human, Pair 14; D015322:Gene Rearrangement, B-Lymphocyte; D015368:Human T-lymphotropic virus 1 / Q000302:isolation & purification; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000175:diagnosis* / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods; D015203:Reproducibility of Results
D007143:Immunoglobulin Heavy Chains