title: Anti-P-glycoprotein antibody-induced apoptosis of activated peripheral blood lymphocytes: a possible role of P-glycoprotein in lymphocyte survival.
abstract: P-glycoprotein (P-gp) is a 170-kDa glycoprotein encoded by the MDR-1 gene. In tumor cells overexpression of P-gp is associated with resistance to chemotherapy-induced apoptosis. P-gp is also expressed on cells of the immune system; however, its role in lymphocyte physiology remains unclear. Therefore, in this investigation, we examined a possible role of P-gp in the survival of in vitro activated peripheral blood mononuclear cells (MNCs). MNCs were activated with anti-CD3 monoclonal antibody (mAb) for 96 hr in the presence or absence of anti-P-gp mAb or isotype control and examined for apoptosis by TUNEL assay. Activation of caspase was determined by colorimetric assay. Activated lymphocytes (96 hr) are resistant to apoptosis. However, anti-P-gp mAb-induced apoptosis in anti-CD3 activated MNC. Induction of apoptosis was associated with increased expression of CD95L; activation of caspase 3, however, did not affect the expression of Bcl-2 and Bcl-xL. Furthermore, both recombinant Fas-Fc fusion protein, a blocker of CD95-CD95L interactions, and Z-DEVD-FMK, a cell-permeable caspase 3 inhibitor, reversed anti-P-gp-induced apoptosis. These data demonstrate that anti-P-gp mAb promotes apoptosis in activated T lymphocytes by up-regulating CD95L expression and via CD95-CD95L interactions and suggest a possible role of P-gp in lymphocyte survival.
authors.affiliation: Department of Medicine, University of California, Irvine 92697, USA.
authors.forename: S
authors.initials: S
authors.lastname: Gollapud
authors.forename: S
authors.initials: S
authors.lastname: Gupta
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000276:immunology / Q000502:physiology*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D017209:Apoptosis; D017252:CD3 Complex / Q000276:immunology; D053148:Caspase 3; D020169:Caspases / Q000502:physiology; D002478:Cells, Cultured; D053222:Fas Ligand Protein; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008214:Lymphocytes / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000502:physiology; D051379:Mice; D019014:fas Receptor / Q000502:physiology
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000911:Antibodies, Monoclonal; D017252:CD3 Complex; C505661:FASLG protein, human; D053222:Fas Ligand Protein; C505658:Fasl protein, mouse; D007376:Interleukin-2; D008562:Membrane Glycoproteins; D019014:fas Receptor; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases