Provocative pattern of rearrangements of the genes for the gamma and beta chains of the T-cell receptor in human leukemias.

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Abstract
To examine the distribution of rearrangements of the .gamma.- and .beta.-chain T-cell receptor (TCR) genes in T- and non-T acute lymphoblastic leukemias (ALLs), and potentially to determine which genes rearrange first in ontogeny, we analyzed high molecular weight DNA from 102 patients with acute leukemia. Rearranged .gamma.- and .beta.-chain genes were found in all T-cell ALLs (22/22) examined. Overall, 27% (18/66) of B-lineage ALLs had .beta.-chain gene rearrangements, and 41% (24/58) had .gamma.-chain gene arrangements, but the distribution of rearranged genes varied according to the stage of B-cell differentiation. The .gamma.-chain genes were rearranged in 11% (1/9) of the B-lineage patients negative for the common acute lymphoblastic leukemia antigen (cALLA) and 50% (23/46) of cALLA+ ALL patients, while the .beta.-chain genes were not rearranged in any of the 7 cALLA- ALL patients examined but were rearranged in 32% (18/56) of the cALLA+ patients. Neither TCR gene was found to be rearranged in acute nonlymphoid leukemia patients (0/12) or in patients with B-cell (surface immunoglobulin-positive) leukemia (0/3). Of the 44 cALLA+ patients in which a direct comparison of .gamma.- and .beta.-chain gene rearrangements could be made, 34% had both genes arranged, 16% had only .gamma.-chain gene rearrangements, and the remaining 50% had both genes in the germ-line configuration. .beta.-Chain rearrangements have not been found in the absence of .gamma.-chain rearrangements. A provocative finding was that only a small percentage (11%) of the patients with cALLA- B precursor cell ALLs had rearranged TCR genes, while 50% of the cALLA+ leukemia patients had at least .gamma.-chain rearrangement, raising a question as to whether indeed cALLA- cells are precursors to cALLA+ cells. Interestingly, 18% (2/11) of the cytoplasmic immunoglobulin (cIg)-positive cALLA+ (pre-B) ALLs involved TCR gene rearrangements, compared to 60% (21/35) of the cIg-negative cases, suggesting the possibility that the majority of functional B cells are derived from the cALLA+ pool that contains immunoglobulin but not TCR gene rearrangements.