PRACTICE Hypersensitivity Flashcards
A 21-year-old woman is stung by a bee. Within 5 minutes she develops severe dyspnea. On her skin are blotchy areas of erythema. She is given an injection of epinephrine and improves over the next 30 minutes. She receives therapy over the next year in which she receives small injections of bee venom. The most likely goal of this therapy is replacement of which of the following forms of immunoglobulin on her mast cells?
IgE
She has type I hypersensitivity. She has increased amounts of IgE bound to perivascular mast cells in her airways. Upon encounter with a specific antigen, the antigen binds to IgE and the mast cells degranulate, releasing vasoactive amines which mediate the symptoms through edema. By ‘desensitizing’ her with injection of small amounts of the allergen, it is hoped that there will be gradual replacement of the IgE with IgG, so that subsequent antigen encounters will not be life-threateni
A 7-year-old child has developed a fever and increasing dyspnea for the past month. On physical examination her temperature is 38 C. She has inspiratory wheezes on auscultation of the chest. A chest radiograph shows marked hilar lymphadenopathy and a peripheral right middle lobe granuloma. Her tuberculin skin test is positive. Which of the following forms of immunologic hypersensitivity reaction is she most likely to have?
type 1,2,3,4?
Granulomatous inflammation is a form of type IV hypersensitivity reaction, with participation by CD4 and CD8 lymphocytes and recruitment and transformation of macrophages.
A 30-year-old man has become more irritable and restless over the past 4 months. He has experienced mild diarrhea. He has lost 4 kg without dieting. On physical examination there is diffuse enlargement of his thyroid gland. Which of the following immunologic mechanisms is most likely to cause his findings?
a. anti receptor antibody b. cd8 lymphocyte mediated cell lysis c. immune complex complement activation d. macrophage acitvation by IFN y e. mast cell degranulation with release of cytokines
A.
TYPE 2 hypersensitivity
NONTOXIX mechanism
He has Graves disease of the thyroid. There is antibody directed against TSH receptor which stimulates the TSH receptor to cause increased production and release of thyroxine, with resultant features of hyperthyroidism
Leukotrienes cause …
bronchoconstriction
A 16-year-old girl has noted passing dark coloured urine for the past 2 days. On physical examination she has periorbital edema. A urinalysis reveals proteinuria and hematuria. A renal biopsy is performed and shows irregular deposition of immune complexes containing IgG and complement. The glomeruli have many neutrophils. Which of the following is the most likely diagnosis?
a. anti glomerular basement membrane
b. food allergy
c. post infectious glomerulonephritis
c. pulmonary tuberculosis
e. type 1 diabetes
C.
A recent infection, often with an organism such as group A streptococcus with pharyngitis, can lead to antibody production with cross-reactivity of antibodies to glomerular antigens and immune complex formation. The immune complexes attract neutrophils via complement activation and Fc receptors on the immune complexes.
