Type I Hypersensitivity and Allergic Reactions

They secrete proteases that cause tissue damage.

It is characterized by edema in tissues, a drop in blood pressure, respiratory distress, and urticarial rash.

They cause red, itchy, tearing eyes and increase mucus secretion, leading to nasal congestion, coughing, and sneezing.

<p>Symptoms include difficulty in breathing and wheezing due to smooth muscle contraction and inflammation.</p> Signup and view all the answers

<p>To determine the causative allergens involved in hypersensitivity reactions.</p> Signup and view all the answers

<p>Allergens are applied by pricking the skin with sterile lancets on the forearm or back.</p> Signup and view all the answers

<p>They can cause abdominal cramps, pain, diarrhea, vomiting, or potentially lead to skin reactions like urticaria.</p> Signup and view all the answers

<p>Immediate release of mediators results in severe vasodilatation and drop in blood pressure.</p> Signup and view all the answers

<p>IgE antibodies bind to mast cells and basophils, leading to sensitization and triggering degranulation upon subsequent exposure to the allergen.</p> Signup and view all the answers

<p>Physiological mediators such as histamine, leukotrienes, and prostaglandins are released during mast cell degranulation.</p> Signup and view all the answers

<p>Genetic predisposition determines an individual's susceptibility to developing allergic reactions upon exposure to allergens.</p> Signup and view all the answers

<p>The immediate response involves cross-linking of IgE antibodies by the allergen, which triggers mast cell degranulation within minutes.</p> Signup and view all the answers

<p>Common allergens include plant pollen, certain foods, bee venom, and medications like penicillin.</p> Signup and view all the answers

<p>The late-phase reaction involves the recruitment of leukocytes, mainly eosinophils and neutrophils, stimulated by cytokines released from mast cells.</p> Signup and view all the answers

<p>TH2 cells secrete interleukins that activate B cells to produce IgE antibodies, playing a crucial role in the allergic response.</p> Signup and view all the answers

<p>Vasodilation and increased vascular permeability occur, leading to symptoms such as swelling and redness at the site of the reaction.</p> Signup and view all the answers

<p>The Fc region of antibodies binds to Fc receptors on NK cells, macrophages, or neutrophils, promoting cell killing through the release of perforins and granzymes.</p> Signup and view all the answers

<p>C3b acts as an opsonin that enhances phagocytosis by marking pathogens for destruction by immune cells.</p> Signup and view all the answers

<p>Transfusing incompatible blood groups can cause hemolysis of red blood cells due to pre-existing antibodies, leading to serious transfusion reactions.</p> Signup and view all the answers

<p>Hemolytic disease occurs when a Rh-negative mother produces antibodies against Rh-positive fetal blood cells, leading to fetal red blood cell destruction in subsequent pregnancies.</p> Signup and view all the answers

<p>The Coombs' test detects antibodies bound to the surface of red blood cells, confirming the presence of an immune-mediated hemolytic process.</p> Signup and view all the answers

<p>Exchange transfusion replaces the newborn's Rh-positive red blood cells with Rh-negative cells, reducing the number of hemolysed cells and associated complications.</p> Signup and view all the answers

<p>Rh-negative mothers are given anti-D antibodies within 72 hours postpartum to neutralize fetal red blood cells in their circulation.</p> Signup and view all the answers

<p>Antibodies specific for normal receptors, such as the thyroid stimulating hormone receptor, can interfere with normal cell function, resulting in conditions like Graves' disease.</p> Signup and view all the answers

<p>The wheal size helps assess allergen sensitivity as either mild, moderate, or severe reactions.</p> Signup and view all the answers

<p>Epinephrine relaxes smooth muscles and constricts blood vessels, making it potentially lifesaving during anaphylaxis.</p> Signup and view all the answers

<p>Specific IgE levels indicate sensitivity to particular allergens and can be measured through tests like a radioallergosorbent assay.</p> Signup and view all the answers

<p>Antibodies enhance phagocytosis of the affected cells by acting as opsonins.</p> Signup and view all the answers

<p>Avoiding allergens is the most effective way to prevent allergic reactions from occurring.</p> Signup and view all the answers

<p>Allergen-specific immunotherapy involves repeated exposure to small doses of allergens to decrease specific IgE and increase IgG levels, promoting tolerance.</p> Signup and view all the answers

<p>Antihistamines block the binding of histamine to receptors, alleviating allergy symptoms.</p> Signup and view all the answers

<p>Reactions may develop in about 15 to 20 minutes after exposure to the allergen.</p> Signup and view all the answers

<p>It occurs due to the production of autoantibodies against the patient's own red blood cells.</p> Signup and view all the answers

<p>Penicillin can form a drug-cell complex that triggers an immune response, producing antibodies that lyse red blood cells.</p> Signup and view all the answers

<p>They cross-react with antigens in the heart muscle, causing inflammation and damage to the heart.</p> Signup and view all the answers

<p>Tissue injury occurs through inflammation due to immune complex deposition and complement activation.</p> Signup and view all the answers

<p>ELISA can detect circulating antibodies, while immunofluorescence can identify antibodies and complement in lesions.</p> Signup and view all the answers

<p>Myasthenia gravis is a condition where antibodies inhibit the function of acetylcholine receptors.</p> Signup and view all the answers

<p>Immune complexes cause inflammation within blood vessel walls, leading to leukocyte activation and platelet aggregation.</p> Signup and view all the answers

<p>These agents reduce immune system activity, decreasing inflammation and tissue damage caused by autoantibodies.</p> Signup and view all the answers

<p>The primary mechanism involves the formation of IgG antibodies against foreign serum proteins, leading to the production of soluble immune complexes.</p> Signup and view all the answers

<p>The Arthus reaction occurs when immune complexes form at the injection site following repeated subcutaneous antigen exposure, such as insulin or penicillin.</p> Signup and view all the answers

<p>In bacterial origins, such as post-streptococcal glomerulonephritis, immune complexes primarily form in the kidneys, while in viral conditions, chronic hepatitis is commonly associated with immune complex formation.</p> Signup and view all the answers

<p>Complement component C3 levels may fall significantly during acute immune complex responses and can be detected through single radial immunodiffusion.</p> Signup and view all the answers

<p>Corticosteroids are used to limit inflammation and mitigate tissue damage associated with immune complex formation.</p> Signup and view all the answers

<p>Type IV hypersensitivity does not involve antibodies but is mediated by T cells and macrophages.</p> Signup and view all the answers

<p>CD4+ helper T cells recognize antigens presented by macrophages and secrete cytokines that promote inflammation and further T cell proliferation.</p> Signup and view all the answers

<p>Farmer's lung is a hypersensitivity pneumonitis caused by deposition of immune complexes in the lungs after inhalation of mold spores or pigeon feces.</p> Signup and view all the answers