Sequential analysis of multidrug resistance protein-1 expression and function in cardiac transplant patients: A possible mechanism of therapy-resistant acute rejection

Persistent Link:
http://hdl.handle.net/10150/282822
Title:
Sequential analysis of multidrug resistance protein-1 expression and function in cardiac transplant patients: A possible mechanism of therapy-resistant acute rejection
Author:
Bowers, Mark Charles, 1963-
Issue Date:
1998
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Multidrug resistance protein-1 (mdr1) is a well characterized membrane protein, expressed in a variety of cell types. In cancer cells, an overexpression of mdr1 has the function of conferring drug-resistance. The exact physiological function of mdr1 constitutively expressed in normal cells still remains unclear. A goal of this work was to determine if there is an increase in expression of mdr1, above constitutive levels, on CD4+ and CD8+ T-lymphocytes, following cardiac transplantation. The expression of mdr1 was correlated with episodes of acute cardiac rejection in order to determine if mdr1 has the functional ability to confer immunosuppressive drug resistance. Drug resistant CD4+ and CD8+ T-lymphocytes could explain episodes of acute allograft rejection observed in a number of immunosuppressed patients. Immunochemical techniques measuring mdr1 were performed on endomyocardial biopsy specimens and peripheral blood mononuclear cells (PBMCs) isolated from cardiac transplant patients. Functional mdr1 assays and flow cytometry were performed on PBMCs isolated from cardiac transplant patients prior to transplantation and at longitudinal time points post-transplantation. The expression and function of mdr1 was correlated to the histological diagnosis of acute rejection. Immunochemical analysis of endomyocardial biopsy samples showed mdr1 expression localized on the plasma membrane of graft infiltrating mononuclear cells. Immunochemical analysis of PBMC samples showed a constitutive mdr1 expression on normal volunteer PBMCs and a increased expression of mdr1 on cardiac transplant PBMCs during episodes of acute rejection. Doxorubicin cytotoxicity assays showed an increased drug resistance profile in transplant patients compared to normal individuals. An mdr1 efflux assay demonstrated an increase efflux function in PBMCs during episodes of acute rejection. Flow cytometric analysis showed significant increases in the intensity of mdr1 expression on CD4+ and CD8+ T-lymphocytes in transplant patients compared to normal individuals. Flow cytometry also confirmed a significant increase in both the number of CD4+ and CD8+ T-lymphocytes expressing mdr1 and the intensity of mdr1 on these subtypes for those patients that had an episode of acute rejection compared to those transplant patients with no episodes of acute rejection. Thus, this study demonstrates an overexpression of a functionally active multidrug resistant protein-1 during episodes of acute rejection.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Cell.; Health Sciences, Pharmacology.; Health Sciences, Medicine and Surgery.; Health Sciences, Pathology.; Health Sciences, Immunology.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Pharmacology and Toxicology
Degree Grantor:
University of Arizona
Advisor:
Larson, Douglas F.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleSequential analysis of multidrug resistance protein-1 expression and function in cardiac transplant patients: A possible mechanism of therapy-resistant acute rejectionen_US
dc.creatorBowers, Mark Charles, 1963-en_US
dc.contributor.authorBowers, Mark Charles, 1963-en_US
dc.date.issued1998en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractMultidrug resistance protein-1 (mdr1) is a well characterized membrane protein, expressed in a variety of cell types. In cancer cells, an overexpression of mdr1 has the function of conferring drug-resistance. The exact physiological function of mdr1 constitutively expressed in normal cells still remains unclear. A goal of this work was to determine if there is an increase in expression of mdr1, above constitutive levels, on CD4+ and CD8+ T-lymphocytes, following cardiac transplantation. The expression of mdr1 was correlated with episodes of acute cardiac rejection in order to determine if mdr1 has the functional ability to confer immunosuppressive drug resistance. Drug resistant CD4+ and CD8+ T-lymphocytes could explain episodes of acute allograft rejection observed in a number of immunosuppressed patients. Immunochemical techniques measuring mdr1 were performed on endomyocardial biopsy specimens and peripheral blood mononuclear cells (PBMCs) isolated from cardiac transplant patients. Functional mdr1 assays and flow cytometry were performed on PBMCs isolated from cardiac transplant patients prior to transplantation and at longitudinal time points post-transplantation. The expression and function of mdr1 was correlated to the histological diagnosis of acute rejection. Immunochemical analysis of endomyocardial biopsy samples showed mdr1 expression localized on the plasma membrane of graft infiltrating mononuclear cells. Immunochemical analysis of PBMC samples showed a constitutive mdr1 expression on normal volunteer PBMCs and a increased expression of mdr1 on cardiac transplant PBMCs during episodes of acute rejection. Doxorubicin cytotoxicity assays showed an increased drug resistance profile in transplant patients compared to normal individuals. An mdr1 efflux assay demonstrated an increase efflux function in PBMCs during episodes of acute rejection. Flow cytometric analysis showed significant increases in the intensity of mdr1 expression on CD4+ and CD8+ T-lymphocytes in transplant patients compared to normal individuals. Flow cytometry also confirmed a significant increase in both the number of CD4+ and CD8+ T-lymphocytes expressing mdr1 and the intensity of mdr1 on these subtypes for those patients that had an episode of acute rejection compared to those transplant patients with no episodes of acute rejection. Thus, this study demonstrates an overexpression of a functionally active multidrug resistant protein-1 during episodes of acute rejection.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Cell.en_US
dc.subjectHealth Sciences, Pharmacology.en_US
dc.subjectHealth Sciences, Medicine and Surgery.en_US
dc.subjectHealth Sciences, Pathology.en_US
dc.subjectHealth Sciences, Immunology.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplinePharmacology and Toxicologyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorLarson, Douglas F.en_US
dc.identifier.proquest9912126en_US
dc.identifier.bibrecord.b39123923en_US
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