The immune system review image diversity

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The Immune System Review - Image Diversity: immunoglobulin molecule 15. How do antibodies work to neutralize antigens? Antibodies, or immunoglobulins, act to facilitate the destruction of antigens. They attract phagocytic leukocytes, trigger the attack of specific defense molecules (activation of the complement system) and directly neutralize the toxicity of some antigens. Immune Memory 16. How can a body that previously came into contact with an antigen be immunized against future infections by the same agent? This phenomenon is called immune memory. When an antigen comes into contact with cells of the humoral immune system for the first time, B lymphocytes that are producers of specific immunoglobulins against that antigen multiply and, in days, synthesize their antibodies. This is called primary response. Some of these specific B lymphocytes remain in circulation for a long time, sometimes during the entire life of the individual, and become the memory cells of the immune system. When the body is exposed to the same antigen in the future, the
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production of antibodies will be faster and more intense, since the immune system is already prepared to react against that antigen. This is called the secondary response. 17. How can immune memory be involved in both the effectiveness of vaccines and allergic reactions? Vaccines are controlled inoculations of fragments of infectious agents or inactive infectious agents to induce the primary immune response, the formation of specific memory B lymphocytes against the antigen. Therefore, the body produces immunoglobulins and is prepared to destroy antigens when exposed to new infections by those agents. In allergies, the humoral immune system is sensitized (makes antibodies and specific memory B lymphocytes) against common environmental substances wrongly recognized as antigens. For example, pollen-derived substances, dust particles, compounds present in foods or in medicines, etc. may be recognized as antigens, thus triggering the primary response and creating an immune memory against them that then becomes the cause of the allergy. The more the individual is exposed to those substances, the more intense the immune reaction is. The IgE antibodies that cause the allergy bind to the receptors of leukocytes called mastocytes, whose cytoplasm is full of histamine granules. The antibody-mastocyte bond causes these cells to release a large amount of histamine into circulation, stimulating inflammation and generating allergic symptoms and signs. For this reason, allergies are treated with antihistamines, drugs that block the histamine reaction. Exacerbated allergic reactions, such as the hypersensitivity to some medicines like
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penicillin and sulfas, may cause anaphylactic shock, a severe clinical condition that sometimes results in death. The Cellular Immune Response 18. How different are the actions of antibodies against bacteria and viruses? Why is the cellular immune response activated in the case of chronic viral infection?
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