LYL1, LMO1/2, and TAL1 transcript quantification. Results of RQ-PCR quantification are shown for LYL1 (dark blue), LMO2 (red), TAL1 (cream), and LMO1 (light blue) transcripts from controls (A) and T-ALLs (B). (A) Controls include normal peripheral mononuclear cells (PBL), bone marrow (BM), and thymus, acute myeloid leukemias (AML), and several T- and B-lymphoid and myeloid (My) cell lines, as indicated. LYL1, LMO2, TAL1, and LMO1 quantification in normal, neonatal thymi showed 4000, 500, 60, and 500 mean copy numbers, respectively, whereas higher levels were observed in normal bone marrow (mean: 8.103, 1.104, 4.104, and 4.101, respectively). Because many T-ALL samples were of bone marrow origin and virtually all demonstrated at least 90% blasts, positive cut-off values were set at 10% of the mean for bone marrow samples for TAL1 and 10-fold of mean thymic values for LMO1/2 and LYL1. To compare levels of expression between transcripts, copy numbers were adjusted to give uniform positivity at 10 (4.104 copies for LYL1, 5.103 for LMO1/2, and 4.103 for TAL1). All B-cell lines were negative; 4 T-cell lines expressed TAL1, including 2 with SIL-TAL1 (CEM and RPMI.8402); 2 expressed LMO2 (Molt13 and RPMI.8402), and 2 expressed LMO1 (RPMI.8402 and Jurkat), but none expressed LYL1. (B) Linear, standardized, normalized copy numbers for each T-ALL, classified by genotype and immunophenotype and sorted for age, as shown in years below each histogram, are indicated. ND indicates LMO1 not quantified.
