title: Frozen RPMI 8402 cells: a reliable source of terminal deoxynucleotidyl transferase positive control material.
abstract: A reliable source of positive control material is needed for immunoperoxidase or immunofluorescent terminal deoxynucleotidyl transferase (TdT) assays. The cell line RPMI 8402 was obtained from a patient with acute lymphoblastic leukemia and is positive for nuclear TdT. The kinetics of TdT expression in a series of cultured RPMI 8402 cells and the effect of cryopreservation on TdT expression were evaluated. The highest percentage of TdT+ cells was detected on days 5-8 of RPMI 8402 cell cultures. TdT positivity was preserved for more than 3 years in cells stored in suspension at -70 degrees C, and at least 76 days on slide preparations when fixed with methanol prior to freezing. We conclude that when RPMI 8402 cells with maximum TdT positivity are stored at -70 degrees C, aliquots can be used as a constant source of positive control material thereby eliminating the necessity and expense of a continuing culture system.
mesh_terms: D002453:Cell Cycle; D002460:Cell Line; D004253:DNA Nucleotidylexotransferase / Q000032:analysis* / Q000378:metabolism; D004254:DNA Nucleotidyltransferases / Q000032:analysis*; D005455:Fluorescent Antibody Technique; D005615:Freezing; D006801:Humans; D008214:Lymphocytes / Q000201:enzymology*; D011309:Preservation, Biological
chemical_list: D004254:DNA Nucleotidyltransferases; D004253:DNA Nucleotidylexotransferase