Allergy as a drug target Flashcards
(16 cards)
What is the difference between sensitivity and intolerance?
Sensitivity refers to an exaggerated response to a substance’s normal effects, but it is not an immunological response. Intolerance involves unpleasant symptoms like diarrhea but does not involve the immune system, as seen in conditions like lactose or gluten intolerance.
How do Type 1 hypersensitivity reactions differ from Type 2 hypersensitivity reactions?
Type 1 hypersensitivity reactions are mediated by IgE antibodies and involve mast cell degranulation (e.g., asthma). Type 2 hypersensitivity reactions involve IgG and IgM antibodies targeting cellular antigens, leading to cytotoxicity (e.g., hemolytic transfusion reactions).
What are the characteristics of a Type 3 hypersensitivity reaction?
Type 3 hypersensitivity reactions involve immune complexes formed by IgG, IgM, or sometimes IgA antibodies interacting with antigens. These immune complexes accumulate in tissues, leading to tissue damage mediated by other immune effectors.
What type of immune response is responsible for Type 4 hypersensitivity reactions?
Type 4 hypersensitivity reactions are T-cell-mediated, where activated macrophages and cytotoxic T cells mediate tissue damage. These reactions are delayed and can occur up to 72 hours after exposure (e.g., coeliac disease and type 1 diabetes).
What is atopy, and how does it relate to allergies?
Atopy is the tendency to develop allergic responses. Around 20% to 30% of the UK population is atopic, and it is often inherited. Atopic individuals may develop conditions like allergic rhinitis, eczema, and asthma.
What is the difference between a symptom and a sign in the context of allergies?
A symptom is subjective and reported by the individual (e.g., itching), while a sign is objective and observable by others (e.g., a skin rash or nasal congestion).
What are the common symptoms of food allergies?
Food allergies can cause symptoms like nausea, vomiting, changes in bowel habits, and stomach pain.
What is the first-line treatment for anaphylaxis, and what is the role of an EpiPen?
The first-line treatment for anaphylaxis is the administration of adrenaline (epinephrine) intramuscularly to establish an airway and alleviate symptoms. An EpiPen can be used in the community and is prescribed to individuals with severe allergies or difficult-to-avoid triggers.
What does cross-reactivity mean in the context of allergies?
Cross-reactivity occurs when exposure to one allergen triggers an allergic response to a structurally similar allergen. This phenomenon can occur with certain foods or substances that share similar protein structures.
Which type of hypersensitivity reaction is commonly associated with autoimmune diseases like coeliac disease and type 1 diabetes?
Type 4 hypersensitivity reactions, which are T-cell-mediated, are commonly associated with autoimmune diseases such as coeliac disease and type 1 diabetes.
What role do mast cells play in allergic reactions?
Mast cells are key effector cells in allergic reactions. They release inflammatory mediators like histamine and leukotrienes when they degranulate, leading to symptoms such as swelling, bronchoconstriction, and increased mucus production.
What distinguishes a drug allergy from a drug side effect?
A drug allergy is immune-mediated and requires avoidance of the medication in the future. In contrast, a drug side effect is not immune-mediated and can be common and predictable, varying in severity depending on the drug’s mechanism of action.
What percentage of the population is affected by penicillin allergy, and what is a common misconception?
About 10% of the general population is affected by penicillin allergy. However, fewer than 10% of those who believe they are allergic to penicillin are actually truly allergic.
How is the severity of an allergic reaction determined when it comes to a drug allergy?
The severity of a drug allergy is determined by classifying the reaction, such as whether it involves a skin reaction or more severe responses like anaphylaxis.
What are some common symptoms of anaphylaxis that require immediate medical intervention?
Common symptoms of anaphylaxis include facial swelling, tightening of airways (bronchoconstriction), difficulty breathing, and low blood pressure. These symptoms require immediate treatment with adrenaline.
Why are corticosteroids sometimes given after adrenaline during the management of anaphylaxis?
Corticosteroids are given after adrenaline to reduce inflammation and prevent the late-phase response of anaphylaxis, which may occur hours after the initial reaction.
