Figure 2.

Detection of AML1/ETO⁺ cells in triple-sorted populations from remission or leukemic BM. (A) RT-PCR analysis on purified cells from remission BM. Five hundred HSC, CLP, monocytes, and B cells and 5,000 T cells were triple-sorted and subjected to RT-PCR analysis. Representative data in case 22, who had maintained remission for 80 months at the time of sampling, are shown. The AML1/ETO transcript was sometimes detectable in HSC, CLP, monocytes, and B cells, but not in T cells after the second round of PCR amplification; + and − under each lane depict positive and negative result of PCR, respectively. Data of all cases are summarized in Table 2. Note that MPO gene is not expressed in AML1/ETO⁺ pooled B cells and CLP, which confirms that the samples do not contain myelomonocytic cells. (B) RT-PCR analysis on purified cells from leukemic BM. Representative data in case 5a are shown. All 500 pooled CD34⁺CD38^-/lo and CD34⁺CD38⁺ cells expressed AML1/ETO mRNA, which is detectable by the first round of PCR, and AML1/ETO⁺ B cells were found at a higher frequency compared with those in remission BM as summarized in Table 3. The last five right lanes show results of PCR analysis in two AML1/ETO⁺ and three AML1/ETO^- EBV-transformed B cell lines established from case 1. Note that in these AML1/ETO⁺ B cell lines, AML1/ETO transcripts were detectable by the first round of PCR amplification. GAPDH, glyceraldehyde-3-phosphate dehydrogenase.