Monoclonality in human T-cell disorders

Genotypic and cytogenetic study of acute myelocytic leukemia and chronic myelocytic leukemia in blast crisis: specific delta rearrangement pattern does not involve J delta gene locus

We have analysed the configuration of immunoassociated genes and the karyotypes of 30 patients with acute myelocytic leukemia (AML) and 10 with chronic myelocytic leukemia in blast crisis (CML-BC). In AML, the frequencies of T-cell receptor (TcR) beta, gamma, and delta chain and immunoglobulin heavy and light chain gene rearrangements were 4.2%, 19%, 8%, 10.7% and 10.5%, respectively. In CML-BC, they were 10%, 20%, 40%, 50% and 0%, respectively. Nine patients had abnormalities in chromosome 2, 7 or 14, upon which immunoassociated genes are located. There seems to be no apparent relationship between these chromosome abnormalities and gene rearrangements. In all patients but one (5/6), the delta rearrangement was accompanied by other immunoassociated gene rearrangements. Molecular size analysis revealed specific delta rearranged band(s) (19.5 kb-BamHI and/or 6.9 kb-EcoRI), as commonly detected in B-acute lymphocytic leukemia (ALL). All the patients with the delta rearranged band, however, had a germline configuration of J delta gene loci, suggesting a DD or V(D)D (probably V delta 2(D)D) pattern. This study also indicates that the delta rearrangement is specific in AML or CML-BC and distinct from that in early T leukemia/lymphoma.