Pesticide Mixtures Induce Immunotoxicity: Potentiation of Apoptosis and Oxidative Stress

The three insecticides of interest were lindane (an organochlorine), malathion (an organophosphate) and piperonyl butoxide (PBO; a synergist). Based on minimum cytotoxicity (> LC25), the following concentrations were chosen for the pesticide mixture studies: 70μM lindane (Lind), 50μM malathion (Mal) and 55μM PBO. In the AlamarBlue cytotoxicity assay, individual pesticide and mixtures of malathion/PBO (MP) and malathion/lindane (ML) prompted cytotoxicity with varying intensities (Mal 18.8%, Lind 20.4%, PBO 23.5%, ML 53.6% and MP 64.9%). Cytopathological analysis revealed apoptotic features in treated cells and the DNA Ladder Assay confirmed the presence of DNA fragments. The specific mode of cell death was examined via the 7-aminoactinomycin D (7-AAD) Staining Assay. Apoptosis was detected in each treatment (Mal 6.5%, Lind 12.0%, PBO 13.2%, ML 19.3% and MP 23.4%). Furthermore, 7-AAD staining in combination with fluorescent-labeled monoclonal antibodies, PE-CD45RB/220 and FITC-CD90, was performed. B-cells were more susceptible to Mal and PBO treatments than were T-cells. The pro-oxidant activity of the pesticides was monitored via the Dichlorofluorescin Diacetate assay. Exposure to pesticides for 15 minutes increased H2O2 production above the controls, Mal 21.1%; Lind 10.8%; PBO 25.9%; ML 26.8%; MP 37.8%. The activities of antioxidant enzymes, glutathione peroxidase (GSH-Px) and glutathione reductase (GR) were altered by these treatments. GR was significantly reduced for the pesticide mixtures only (control: 51.7; Mal: 48.2; Lind: 50; PBO: 52.3; ML: 40.5; MP: 42 Units/mg). GSH-Px activity was severely reduced for all the pesticide treatments (control: 44.9; Mal: 30.2; Lind: 30.6; PBO: 32.4; ML: 21.1; MP: 21.1 Units/mg). These results indicate that exposure to these pesticide and pesticide mixtures induces apoptosis and oxidative stress.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Biomedical Sciences and Pathobiology

Department dc:contributor.department

Biomedical Sciences and Pathobiology

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2001

Author dc:creator

• Rabideau, Christine L.

Chair dc:contributor.committeechair

• Misra, Hara P.

Committee members dc:contributor.committeemember

• Crisman, Mark V.
• Gregory, Eugene M.

• antioxidant enzymes
• pesticides
• lindane
• malathion
• piperonyl butoxide
• Apoptosis
• splenocytes
• in vitro
• superoxide dismutase
• glutathione peroxidase
• immune cells
• catalase
• glutathione reductase
• cytotoxicity
• chemical mixtures
• oxidative stress

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-08152001-144213

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/34547