17.5
Allergische Reaktionen: Anaphylaxie
Die Anaphylaxie ist eine schwere, lebensbedrohliche Überempfindlichkeitsreaktion, die durch Immunglobulin E, oder IgE, vermittelt wird. Bindet IgE an…
Anaphylaxie ist eine unmittelbare Überempfindlichkeitsreaktion, die durch IgE-Antikörper vermittelt wird. Diese Antikörper binden an Allergene und bilden Allergen-IgE-Antikörperkomplexe. Häufige Allergene sind Pollen, Hausstaubmilben, Medikamente und bestimmte Lebensmittel.
Diese Komplexe binden an Rezeptoren auf Mastzellen und Basophilen, was zu einer schnellen Degranulation und zur Freisetzung von Histamin, Leukotriene und Prostaglandinen führt.
Diese Mediatoren verursachen Vasodilatation, Bronchokonstriktion, Ödem und Neutrophilenaktivierung und lösen eine Entzündungsreaktion aus.
Diese Reaktionen können die Gefäße, den Magen-Darm-Trakt, die Haut und das Atmungssystem stark beeinträchtigen. Sie können sich auch als Erkrankungen wie Nahrungsmittelallergien, Urtikaria, Rhinitis und Asthma äußern.
Verschiedene Medikamente können Anaphylaxie verursachen, darunter Penicillin, Asparaginase, monoklonale Antikörper, Kortikotropin, Heparin, Impfstoffe, Lokalanästhetika und Antiseptika wie Chlorhexidin.
Diagnostische Methoden für Anaphylaxie sind klinisch und basieren auf den Symptomen. Hauttests, wie die intradermale Injektion von Penicilloylpolylysin, können später eine Penicillinallergie feststellen.
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Q1: What is anaphylaxis and how does it develop?
Anaphylaxis is a severe, immediate hypersensitivity reaction mediated by IgE antibodies. When IgE binds to allergens, it forms complexes that attach to mast cells and basophils, triggering rapid degranulation. This releases mediators like histamine, leukotrienes, and prostaglandins, causing vasodilation, bronchoconstriction, edema, and inflammation throughout the body.
Q2: Which drugs commonly trigger anaphylactic reactions?
Penicillin is responsible for approximately 75% of anaphylactic deaths due to widespread use. Other drugs causing anaphylaxis include asparaginase, monoclonal antibodies, corticotropin, heparin, vaccines, local anesthetics, and antiseptics like chlorhexidine. These reactions occur through IgE-mediated mechanisms similar to food and environmental allergens.
Q3: What body systems are affected during anaphylaxis?
Anaphylaxis primarily affects the cardiovascular, respiratory, gastrointestinal, and integumentary systems. Symptoms include urticarial rash, hives, angioedema, bronchoconstriction, wheezing, shortness of breath, and hypotension. Severe cases progress to anaphylactic shock, characterized by sudden blood pressure drops, respiratory distress, and potential cardiovascular collapse.
Q4: How is anaphylaxis diagnosed in clinical practice?
Anaphylaxis diagnosis is primarily clinical, based on symptom presentation. Skin tests, such as intradermal injection of penicilloylpolylysine, can later identify penicillin allergy. Detecting particular IgE in plasma confirms allergic reactions, though these tests are reserved for cases where the allergen cause remains unclear.
Q5: What are common allergens that cause anaphylaxis?
Common allergens include food items like peanuts and shellfish, environmental substances such as grass pollen and dust mites, insect stings, and pharmaceutical agents. Radiological contrast agents, vaccines, and latex also trigger anaphylaxis. These allergens bind to IgE antibodies, initiating the cascade of mast cell and basophil degranulation.
Q6: What mediators are released during anaphylaxis and what effects do they produce?
Mast cells and basophils release histamine, leukotrienes, and prostaglandins upon degranulation. These mediators cause vasodilation, bronchoconstriction, edema, and neutrophil activation, generating an inflammatory response. The resulting cascade produces symptoms ranging from mild urticaria to life-threatening cardiovascular collapse and respiratory distress.
Q7: How does anaphylaxis differ from other hypersensitivity reactions?
Anaphylaxis is an immediate, IgE-mediated hypersensitivity reaction occurring within minutes of allergen exposure. Unlike delayed hypersensitivity reactions, which develop over hours or days, anaphylaxis causes rapid degranulation of mast cells and basophils. This distinguishes it from other hypersensitivity types in onset speed and severity.