Chapter 19 Disorders of the immune system

How the virus evades the immune system Damages the cell that plays a central role High mutation rate Many strains of the virus are developed. Antibodies that are produced against one strain are not effective against the other strains.

Stay as provirus – hides from the immune system Stay within the vesicles in the host cell. Stimulated the infected cell to fuse with the infected cell. Virus is hopping from one host cell to another. Immune cannot see the virus.

Indirect ELISA is one of the tests used to diagnose HIV infection. Transmitted by sexual contact, blood transfusion. Contaminated needles One of the drugs used to treat the disease zidovudine

HIV infection Divided into 3 categories. Category A – no severe symptoms, swollen lymph nodes. Category B – persistent infection by Candida albicans, diarrhea, fever Category C – AIDS ( acquired immunodeficiency syndrome) Candida infection of the esophagus, tubeculosis, pneumonia.

Hypersensitivity, allergy, anaphylaxis Abnormal immune response IgE antibodies are produced against antigens – pollen, insect venom, fungal spores. First exposure – the person becomes sensitized. Subsequent exposure results in anaphylaxis.

Secondary response is stronger. Antigen binds to IgE antibodies on the mast cells. Large amount of chemical mediators such as histamine. This leads to allergic reaction (anaphylaxis). Symptoms show up within a few minutes after the exposure to the antigen.

Systemic anaphylaxis – caused by injected antigens such as insect venom. For example, some people are allergic to bee sting. The venom binds to IgE present on the surface of mast cells and basophils stimulate them to release a large amount of chemical mediators. Cause damage to the blood vessel – drop in blood pressure known as shock. Treated with epinephrine.

Localized anaphylaxis caused by inhaled antigens such as pollen and fungal spores. Mast cells lining the respiratory tract release histamine. Watery eyes, runny nose, coughing and sneezing. Antihistamine.

Allergic contact dermatitis T cells are involved Reaction to poison ivy is an example. First exposure – might not be any symptoms. Subsequent exposure – response is stronger. Large amount of cytokines are produced. They cause damage to the cells, which results in rash.

Autoimmune disorders Myasthenia gravis – antibodies are produced against one’s own muscles. Death due to respiratory failure. Suppressor cells are not working right. Antibodies are made against one’s own cells.