Expression and function of multidrug resistance P-glycoprotein in a cultured natural killer cell-rich population revealed by MRK16 monoclonal antibody and AHC-52.
Natural killer (NK) cells have been reported recently to be the highest in expressing multidrug resistance (MDR) P-glycoprotein among normal mature lymphoid cells. Using a cultured NK cell-rich population, we have examined the expression and function of P-glycoprotein, in particular its role in NK cell-mediated cytotoxicity, by employing two MDR-reversing agents (nicardipine and AHC-52, a nicardipine analog almost devoid of calcium channel blocking activity) and monoclonal antibody against P-glycoprotein (MRK-16). The expression of P-glycoprotein was detected by flow cytometry and polymerase chain reaction of reverse transcribed mRNA. P-glycoprotein was functional in terms of rhodamine dye excretion and its susceptibility to the MDR-reversing agents. Since the concentration of nicardipine required for 50% inhibition (IC50) of rhodamine dye excretion (2 microM) was close to that of AHC-52 (5 microM), it was suggested that their inhibitory effects were not due to calcium channel blocking activity, and that ACH-52 is a selective inhibitor for P-glycoprotein. The IC50 of nicardipine for NK cell-mediated cytotoxicity (33 microM) was also close to that of AHC-52 (26 microM), indicating that P-glycoprotein is involved in NK cell-mediated cytotoxicity. In support of this, MRK16 inhibited NK cell-mediated cytotoxicity in a concentration-dependent manner. Both binding of target cells to NK cells and post-binding events were affected by AHC-52, suggesting that P-glycoprotein is involved in several steps in NK cell-mediated cytotoxicity.
Department of Biomolecular Science, Faculty of Science, Toho University, Chiba, Japan.
Y
Y
Kobayashi
T
T
Yamashiro
H
H
Nagatake
T
T
Yamamoto
N
N
Watanabe
H
H
Tanaka
K
K
Shigenobu
T
T
Tsuruo
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D000911:Antibodies, Monoclonal; D001483:Base Sequence; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D004095:Dihydropyridines / Q000494:pharmacology*; D004351:Drug Resistance; D005434:Flow Cytometry; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000494:pharmacology; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011720:Pyrazoles / Q000494:pharmacology*; D020112:Rhodamine 123; D012235:Rhodamines
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000911:Antibodies, Monoclonal; D004095:Dihydropyridines; D007140:Immunoglobulin Fab Fragments; D011720:Pyrazoles; D012235:Rhodamines; C059017:AHC 52; D020112:Rhodamine 123