Analysis of T-cell receptor delta chain gene in hematological malignancies

We analyzed the rearrangement of TcR delta chain gene in 179 cases of hematological malignancies. In 17 T-cell lines, RPMI 8402, DND41, Peer, and Molt 13 had delta rearranged band (s). Except for RPMI 8402, these cell lines expressed functional delta gene. All of those gamma delta-T-cell lines had short message (1 kb) of TcR beta gene. These findings suggest differences between alpha beta-T-cells and gamma delta-T-cells. All 9 cases of T-ALL/LBL, of which 4 had neither gamma nor beta gene rearrangement, had a new rearranged band of TcR delta locus. This rearrangement was observed in 63% of B-lineage ALL/LBL. In the other T-lymphoproliferative disorders, only 2 cases of AILD and 1 of T-cell lymphoma had the rearranged band (s), showing derived T-cell neoplasm from gamma delta-T-cell as minority. In B-leukemia/lymphoma and myelocytic leukemia, 15% of the cases had the delta rearrangement. Heterogenous findings of TcR delta locus analysis were observed in ATLL without proviral HTLV-I DNA, T-cell lymphoma, AILD and HD. The J delta 1 region was frequently used and the J delta 2 region was rearranged in one AILD. It is suspected that J delta 3 was used in one T-ALL/LBL. There was no correlation between the phenotypic pattern of CD3, CD4, and CD8 in T cell disorders and the rearrangement of the TcR delta gene. These findings suggest that the newly identified TcR delta chain gene rearranges at a very early stage of T cell ontogeny; prior to the other TcR genes and perhaps at almost the same differentiation level as that of CD7 expression. The TcR delta gene is useful in evaluating clonality for the most immature T cell neoplasms not showing rearrangement of the other TcR genes. This gene is not lineage specific, however, when used in conjunction with IgHC gene, it may be a useful tool for the study of ALL/LBL.