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Chapter 9: Alterations in Immunity

Terms in this set (35)

Inappropriate immune responses are misdirected responses against the host's own tissues
Autoimmunity
directed responses against beneficial foreign tissues, such as transfusions or transplants.
immune system's reaction against antigens on the tissues of other members of the same species.
Alloimmunity
exaggerated responses against environmental antigens
Allergy
insufficient responses to protect the host
Immune Deficiency
(IgE-mediated) reactions
Type 1
(tissue-specific) reactions,
Type 2
(immune complex-mediated) reactions
Type 3
(cell-mediated) reactions.
Type 4
the most rapid immediate hypersensitivity reaction, is an explosive reaction that occurs within minutes of reexposure to the antigen and can lead to cardiovascular shock.
Anaphylaxis
ntigens that cause allergic responses.
Allergens
IgE-mediated) hypersensitivity reactions are mediated through the binding of IgE to Fc receptors on mast cells and cross-linking of IgE by antigens that bind to the Fab portions of IgE. Cross-linking causes mast cell degranulation and the release of histamine (the most potent mediator) and other inflammatory substances.
Type 1 Hypersensitivity
acting through the H1 receptor, contracts bronchial smooth muscles, causing bronchial constriction; increases vascular permeability, causing edema; and causes vasodilation, increasing blood flow into the affected area. Histamine with H2 receptors results in increased gastric acid secretion and a decrease of histamine released from mast cells and basophils.
Histamine
reactions are caused by five possible mechanisms: complement-mediated lysis, opsonization and phagocytosis, neutrophil-mediated tissue damage, antibody-dependent cell-mediated cytotoxicity, and modulation of cellular function.
Type 2 Hypersensitivity
hypersensitivity reactions are caused by the formation of immune complexes that are deposited in target tissues, where they activate the complement cascade, generating chemotactic fragments that attract neutrophils into the inflammatory site. Neutrophils release lysosomal enzymes that result in tissue damage.
Type 3 Hypersensitivity
cell-mediated) hypersensitivity reactions are caused by either cytotoxic T lymphocytes (Tc cells) or lymphokine-producing Th1 cells.
Type 4 Hypersensitivity
pollen, molds and fungi, certain foods (milk, eggs, fish, peanuts), animals, certain drugs, cigarette smoke, and house dust.
Type 4 typical Allergens
usually are confined to the areas of initial intake or contact with the allergen.
Ingested allergens induce gastrointestinal symptoms, airborne allergens induce respiratory tract or skin manifestations, and contact allergens induce allergic responses at the site of contact.
Type 4 hypersensitivity Clinical Manifestations
riginate from the coincidence of an initiating event in a genetically predisposed individual leading to an autoimmune mechanism that affects specific target tissues or cells.
Autoimmune disease
develops during the embryonic period.
Central Tolerance
maintained in secondary lymphoid organs by regulatory T lymphocytes or antigen-presenting dendritic cells.
Peripheral Tolerance
Include transient neonatal disease, in which the maternal immune system becomes sensitized against antigens expressed by the fetus; transplant rejection; and transfusion reactions, in which the immune system of the recipient of an organ transplant or blood transfusion reacts against foreign antigens on the donor's cells.
Alloimmune Disorders
Chronic, multisystem, inflammatory disease and is one of the most serious of the autoimmune disorders.
Characterized by the production of a large variety of autoantibodies.
SLE
immediate and rare, acute rejection is cell mediated and occurs days to months after transplantation, and chronic rejection is caused by inflammatory damage to endothelial cells as a result of a weak cell-mediated reaction.
Hyperacute Graft Rejection (preexisting antibody)
the targets of autoimmune or alloimmune reactions. The most important of these, because they provoke the strongest humoral immune response, are the ABO and Rh systems.
Red Blood Cell Antigens
What complexes are the most likely to have severe pathologic consequences?
Intermediate size immune complexes
caused by genetic defects that disrupt lymphocyte development,
Congenital (primary immune deficiency)
secondary to disease or other physiologic alterations.
Acquired Secondary Immune Deficiency
caused by superimposed conditions, such as aging, malnutrition, infections, malignancies, physical or psychologic trauma, environmental factors, some medical treatments, or other diseases.
Acquire Immunodeficnecy
Disorders are characterized by abnormally high levels of inflammation secondary to mutations in control of inflammasome activation or in defects in cellular receptors of cytokines designed to decrease inflammation.
Autoinflammatory Disorders
Which include insufficient numbers of phagocytes or defects of chemotaxis, phagocytosis, or killing, can result in recurrent life-threatening infections such as septicemia and disseminated pyogenic lesions
Defect în phagocyte function
total lack of T-cell function and a severe (either partial or total) lack of B-cell function.
SCID
(congenital thymic aplasia or hypoplasia) is characterized by complete or partial lack of the thymus (resulting in depressed T-cell immunity) and the parathyroid glands (resulting in hypocalcemia) and the presence of cardiac anomalies.
DiGeorge Syndrome
rejection is immediate and rare
Hyperacute graft rejection
cell mediated and occurs day to months after transplantation
Acute Rejection
Rejection caused by cell inflammatory damage to endothelial cells as a result of weak cell-mediated reaction
Chronic Rejection
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