T‐cell Receptor β‐Chain Gene Expression in B‐lineage Acute Lymphoblastic Leukemia

The T‐cell receptor β‐chain (Tβ) gene expression was examined in 16 children with B‐lineage acute lymphoblastic leukemia (ALL), including eight patients with rearrangement of the Tβ gene as well as immunoglobulin (Ig) heavy chain gene rearrangement. In contrast to the 1.3 kb full‐length transcripts of the Tβ gene observed in T‐lineage leukemia and lymphoma cells, no transcript of the Tβ gene was detected in 10 patients, including four with Tβ gene rearrangement. Low levels of Tβ transcripts were found in three patients with Tβ gene rearrangement and two patients without Tβ gene rearrangement, but those transcripts were truncated. In contrast to those findings, a single patient with Tβ gene rearrangement showed abundant 1.3 kb Tβ transcripts. These data indicate that Tβ gene expression is not restricted to T‐lineage cells and demonstrate the heterogeneity of B‐lineage ALL at the expression level of the Tβ gene. Our findings also suggest that Tβ gene expression is not always accompanied with Tβ gene rearrangement.