Rearrangement of T-cell receptor delta chain gene as a marker of lineage and clonality in T-cell lymphoproliferative disorders.

We analyzed the rearrangement of T-cell receptor (TcR) delta chain gene in 88 cases of lymphoproliferative disorders; 31 acute lymphoblastic leukemias/lymphoblastic lymphomas (ALL/LBL); 27 adult T-cell leukemias/lymphomas, 9 angioimmunoblastic lymphoadenopathies (AILD); 10 T-cell lymphomas (non-Hodgkin's lymphoma); and 11 Hodgkin's disease. All of 9 T-ALL/LBL cases, of which 4 cases have neither beta nor gamma gene rearrangement, had a new rearranged band of TcR delta locus. Ten of 16 B-lineage ALL/LBL had rearranged band(s) or deletion of TcR delta locus. The rearranged bands were recognized in 2 cases of AILD and 1 case of T-cell lymphoma. All cases of adult T-cell leukemias/lymphomas, 4 of AILD, 4 of T-cell lymphoma, and 8 of Hodgkin's disease had deleted TcR delta locus. Heterogeneous findings of TcR delta locus analysis were observed in AILD, T-cell lymphoma, and Hodgkin's disease. In 16 cases with TcR delta rearrangement, 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, 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 stage with CD7 expression. The TcR delta gene is useful in assessing 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 immunoglobulin heavy chain gene, it may be a useful tool to distinguish lymphoid lineage of ALL/LBL.