DETECTION OF NEUROBLASTOMA-CELLS IN BONE-MARROW AND PERIPHERAL-BLOOD AT DIAGNOSIS BY THE REVERSE TRANSCRIPTASE-POLYMERASE CHAIN-REACTION FOR TYROSINE-HYDROXYLASE MESSENGER-RNA

Background, Bone marrow metastasis often occurs in patients with neuro blastoma; therefore, a sensitive assay to detect occult neuroblastoma cells in bone marrow (BM) and peripheral blood (PB) is needed, The fea sibility and clinical value of using the reverse transcriptase-(RT) po lymerase chain reaction (PCR) to amplify mRNA for tyrosine hydroxylase (TH), the first enzyme of catecholamine synthesis, was evaluated to d etect neuroblastoma cells in patient samples. Methods. Thirty-eight pa tients with Stages I to IV neuroblastoma and eight healthy donors were included in this study. Bone marrow and PB samples obtained at diagno sis were examined for TH mRNA. After preparation of complementary DNA, the PCR was performed to amplify the TH gene. Results. Tyrosine hydro xylase mRNA was detected in neuroblastoma samples including a cell lin e and tumor tissues, but was not detected in normal BM or PB mononucle ar cells, Neuroblastoma cells were detected at a level of 1 per 10(5-6 ) normal PB mononuclear cells by this method, Tyrosine hydroxylase mRN A was detected in 18 of 38 BM samples, and all 12 BM samples with cyto logic evidence of tumor cells were positive for TH mRNA by the RT-PCR, Six of 26 patients without cytologic evidence of tumor cells in the B M were also positive for TH mRNA. TH mRNA was detected in BM samples f rom 1 of 14 patients with Stage I disease, 2 of 7 patients with Stage II disease, 1 of 3 patients with Stage III disease and all patients wi th Stage IV (11 patients) and IVS (3 patients) diseases. Tyrosine hydr oxylase mRNA also was detected in 8 of 14 PB samples (one of five pati ents in Stages I, II or III, and 7 of 9 in Stage IV or IVS). Conclusio ns. Reverse transcriptase-polymerase chain reaction amplification of T H mRNA was a sensitive and specific method of detecting occult neurobl astoma cells in BM and PB samples, Neuroblastoma cells could be detect ed by this method in some BM samples that had no cytologic evidence of tumor cells and in some PB samples at the time of diagnosis. The clin ical significance of these very low levels of neuroblastoma cells dete cted by RT-PCR requires further investigation.