DIFFERENT T-CELL RECEPTOR GENE CONFIGURATIONS IN T-CELL NEOPLASMS AND ACUTE LYMPHOBLASTIC-LEUKEMIA

Southern blotting and multiple restriction enzymes were used to analyze T-cell receptor (TCR) and immunoglobulin heavy chain genes in 20 postthymic T-cell neoplasms, ten prethymic and thymic T-cell tumors, and 45 cases of precursor-B acute lymphoblastic leukemia (ALL). Immunoglobulin heavy chain, never rearranged in a postthymic specimen and only once in a prethymic/thymic sample, was rearranged in all but two cases of precursor-B ALL. In contrast, biallelic rearrangement of TCR-beta with deletion of the first constant region germline fragment was regularly seen in T-cell neoplasms, but only twice in the 45 precursor-B ALL cases. TCR-gamma was rearranged in all but one postthymic sample, in all prethymic/thymic samples, and in approximately half of precursor-B ALL specimens as well. Preferential use of V-gamma regions was evident among the various disorders: V8 and V10 in postthymic neoplasms; and V3, V5, V7, and, particularly, V9 in precursor-B ALL. In all the studied conditions, TCR-delta was rarely in germline configuration. Extensive biallelic deletion of J-delta-1, J-delta-2, and C-delta, almost always (19 of 20 specimens) present in postthymic neoplasms, was observed in only a minority (14 of 45) of precursor-B ALL samples. In precursor-B ALL, rearranged antigen receptor genes were more frequently found in common acute lymphoblastic leukemia antigen-positive and terminal deoxynucleotidyl transferase-positive specimens. Furthermore, TCR gene rearrangement in that disorder was characterized by a hierarchical pattern: TCR-beta was not rearranged without TCR-gamma nor TCR-gamma without TCR-delta. Despite uncertainty of the mechanism, the various disorders can be distinguished on the basis of characteristic antigen receptor gene patterns.