title: New flow cytometric method for detection of minimally expressed multidrug resistance P-glycoprotein on normal and acute leukemia cells using biotinylated MRK16 and streptavidin-RED670 conjugate.
abstract: To evaluate the expression of multidrug resistance (MDR) on normal and leukemia cells, we examined P-glycoprotein (P-gp) by a newly devised flow cytometric method, utilizing a biotinylated monoclonal antibody (mAb) against P-gp (MRK16), a streptavidin-RED670 conjugate (SA-RED670) and appropriate emission filters. The combination of biotinylated MRK16 (b-MRK16) and SA-RED670 resulted in higher sensitivity as compared with standard methods such as the use of streptavidin-phycoerythrin (SA-PE) conjugate. The sensitivity was examined in K562, K562/ADR, NOMO-1, NOMO-1/ADR and HL60 cells, and compared with the data obtained from reverse transcription polymerase chain reaction (RT-PCR) of mdr-1 gene. P-gp positivity on flow cytometry was 10.4%, 99.9%, 1.4%, 90.4% and 0%, respectively. Mdr-1 mRNA was well expressed in K562/ADR and NOMO-1/ADR cells, but not in NOMO-1 and HL60 cells. In K562 cells, mdr-1 was found after 40 cycles of PCR, but not 25 cycles. These data are well correlated with those from the flow cytometry. We then studied the P-gp expression on normal peripheral blood cells and acute leukemia cells. P-gp was little expressed on peripheral lymphocytes, monocytes and granulocytes. It was also little expressed on blast cells from 5 patients with acute promyelocytic leukemia (AML) and 5 acute lymphocytic leukemia (ALL) expressed P-gp at diagnosis, ranging from 8.5% to 34.5% (16.9 +/- 11.8%) and from 2.3% to 45.6% (24.0 +/- 17.8%), respectively. All 9 relapsed or refractory cases expressed P-gp, ranging from 21.1% to 99.8% (52.2 +/- 29.9%). Significant differences were found in APL, CD34-positive and relapse and refractory cases (P = 0.0006, 0.0007 and 0.0088, respectively). These results indicate that this flow cytometric analysis is useful for the evaluation of clinical MDR status and can identify a group of patients with resistant leukemia.
authors.affiliation: Department of Medicine III, Hamamatsu University School of Medicine.
authors.forename: A
authors.initials: A
authors.lastname: Takeshita
authors.forename: K
authors.initials: K
authors.lastname: Shinjo
authors.forename: K
authors.initials: K
authors.lastname: Ohnishi
authors.forename: R
authors.initials: R
authors.lastname: Ohno
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000032:analysis*; D000208:Acute Disease; D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins; D002460:Cell Line; D018432:Drug Resistance, Multiple; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D007938:Leukemia; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive; D015473:Leukemia, Promyelocytic, Acute; D016133:Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D019809:Streptavidin; D014407:Tumor Cells, Cultured
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins; D019809:Streptavidin