Week_12_-_Immune_responses_to_toxicants - Week 12 - Immune...

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Week 12 - Immune responses to toxicants Immune responses to toxicants can be divided into two broad categories: suppression or stimulation of the immune system. Immunosuppression Inhibition of immune system function, either through decreased activity or responsiveness of immune system cells, or through decreased numbers of immune system cells, is termed immunosuppression. Immunosuppression weakens the body’s ability to fight off invaders, and increases the likelihood of secondary infections caused by viruses or bacteria. Immunosuppression can occur through damage to the primary or secondary lymphoid organs, and in some cases toxicants may affect many components of the immune system simultaneously. For example, polychlorinated biphenyls (PCBs) cause damage to both primary and secondary lymphoid organs in experimental animals. PCB exposure in these animals causes decreased circulating immunoglobulins in the serum and diminished antibody response following exposure to antigens. Similar effects are observed in people and animals exposed to polybrominated biphenyls . Immunosuppression can occur from damage to primary lymphoid organs alone. For example, the organic solvent benzene targets the bone marrow, resulting in aplastic anemia , which is the inability of the body to produce new blood cells of all types. Bone marrow toxicity is observed in both humans and animals, and is hypothesized to be
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This note was uploaded on 02/10/2012 for the course PHY 495 taught by Professor Hess during the Summer '11 term at Alabama.

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Week_12_-_Immune_responses_to_toxicants - Week 12 - Immune...

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