RQ-PCR analysis of pTα and RAG-1 transcripts.
RAG-1 (shaded triangles) and pTα (shaded circles) expression in T-ALLs, acute myeloid leukemia (AML), healthy circulating PBMCs, and bone marrow (BM) controls. The HPB-ALL cell line expressed high-level pTα and RAG-1 and was arbitrarily attributed a value of 100%; all results were expressed relative to this value. Linearity of HPB-ALL quantitation for both transcripts extended over 5 logs. Low levels of pTα expression, 2 to 3 logs below HPB-ALL, were seen in normal PBMCs and most normal bone marrow samples, with a mean ± SD for all 15 samples of 0.55% ± 0.5%. AML samples expressed lower levels. RAG-1 transcripts were virtually undetectable in PBMCs and were at least 3 logs lower than HPB-ALL in the AML samples tested. Variable low-level expression (mean, 3.5% ± 4.5%) was seen in normal bone marrow because of the presence of lymphoid lineage precursors. pTα values at least 2 logs lower than HPB-ALL were considered negative. RAG1 values at least 2 logs lower than HPB-ALL were considered low/negative, bone marrow values between 1% and 15% were considered uninterpretable, and PB T-ALL values greater than 1% or BM T-ALLs greater than 15% (1.5 × 10−1) were considered positive. All results, including those considered uninterpretable, are shown. Mean value for each category is indicated as a horizontal bar.
