Hypersensitivity Flashcards
What is hypersensitivity?
Heightened immune responsiveness against harmless antigens
Test is preferred for skin testing in immediate hypersensitivity?
Percutaneous (prick method)
Positive skin test result identified?
Wheal and flare (redness and swelling)
In vitro test for total serum IgE?
Radioimmunosorbent Test (RIST)
Purpose of RAST test?
Measures specific IgE antibodies
Primary mediators of Type I hypersensitivity?
Histamine, Heparin, Eosinophil Chemotactic Factor (ECF-A), Neutrophil Chemotactic Factor (NCF-A)
Secondary mediators of Type I hypersensitivity?
Prostaglandins, Leukotrienes, Platelet Activating Factor, IL-1, IL-3, IL-4
Cells involved in degranulation for Type I hypersensitivity
Mast cells and basophils
Type II hypersensitivity is mediated by
Antibodies against antigens on cell surface causing cytolysis
Type III hypersensitivity involves
Soluble antigens and the deposition of Ag-Ab complexes in tissues
Type IV hypersensitivity is mediated by
T-cells
Type of hypersensitivity involving Hemolytic Transfusion Reactions (HTR), Autoimmune Hemolytic Anemia (AIHA), Paroxysmal Cold Hemoglobinuria (PCH), Cold Agglutinins
Type II hypersensitivity
Tests for Type II hypersensitivity
Direct and Indirect Antihuman Globulin (AHG) test
Test for Type III hypersensitivity
Labelled immunoassays
Type IV hypersensitivity is mediated by
T-cells
Antigens involved in Type IV hypersensitivity
Intracellular pathogens (bacteria, fungi, parasites, viruses), Contact antigens (poison ivy, metal)
Confirmatory test for contact dermatitis in Type IV hypersensitivity
Patch test
Type I hypersensitivity involves
Antibody production
Type IV hypersensitivity involves
T-cell memory and Ab specificity
Tuberculin test result for Type IV hypersensitivity
NTP > 10 mm (+) or > 15 mm
Type I, II, III are mediated by
Antibodies
Type of hypersensitivity involving: Anaphylaxis, hay fever, food allergies, asthma
Type I
Type of hypersensitivity: Transfusion reactions, autoimmune hemolytic anemia, hemolytic disease of newborn, thrombocytopenia
Type II
Type of hypersensitivity: Serum Sickness, Arthus reaction, Systemic Lupus Erythematosus
Type III
Type of hypersensitivity: Contact dermatitis, tuberculin test, pneumonitis, allergy or infection
Type IV
Types of hypersensitivity that are antibody mediated
Type I, II, III
Type of hypersensitivity that is cellular mediated
Type IV
Immune component involved in Type II and III hypersensitivity
Complement
