Detection of minimal residual T cell acute lymphoblastic leukemia by flow cytometry.
We have developed a flow cytometric assay for the determination of cellular expression of terminal deoxynucleotidyl transferase (TdT) and applied this to the detection of minimal residual T cell acute lymphoblastic leukemia (T-ALL). The flow cytometric assay for TdT demonstrated requisite specificity: TdT was localized to the nucleus, and was detected in MOLT3 T lymphoblasts, clinical T-ALL samples, and normal bone marrow B lymphoid precursors, but in neither the KG1a myeloid leukemia cell line nor normal myeloid cells. Co-expression of TdT and the pan T cell marker CD5 was used to quantify T lymphoblasts. 0.25 +/- 0.13% of normal adult bone marrow CD5+ cells were TdT+; these may represent early T lymphoid precursors. When admixed with normal bone marrow, CD5+TdT+ leukemic cells could be detected above background levels at an added concentration of 0.035% (95% confidence interval 0.028-0.43%). Long term follow-up of a large number of patients will be required to determine the clinical significance of a minimal burden of leukemic cells.
Johns Hopkins Oncology Center, Baltimore, MD 21205.
S D
SD
Gore
M B
MB
Kastan
S N
SN
Goodman
C I
CI
Civin
D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000032:analysis; D018952:Antigens, CD34; D000943:Antigens, Differentiation / Q000032:analysis; D000951:Antigens, Neoplasm / Q000032:analysis; D001853:Bone Marrow / Q000473:pathology; D001854:Bone Marrow Cells; D004253:DNA Nucleotidylexotransferase / Q000032:analysis*; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D015459:Leukemia-Lymphoma, Adult T-Cell / Q000175:diagnosis* / Q000201:enzymology / Q000473:pathology; D015260:Neprilysin; D013601:T-Lymphocytes / Q000737:chemistry*; D013997:Time Factors; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D018952:Antigens, CD34; D000943:Antigens, Differentiation; D000951:Antigens, Neoplasm; D004253:DNA Nucleotidylexotransferase; D015260:Neprilysin