Pathology bootcamp
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Questions and Answers

What is the most likely underlying condition in this infant?

  • Hyper IgE syndrome
  • Severe combined immunodeficiency
  • Leukocyte adhesion deficiency (correct)
  • Chronic granulomatous disease

    • What is the significance of the positive nitroblue tetrazolium dye reduction test?

  • It confirms the diagnosis of chronic granulomatous disease (correct)
  • It indicates a defect in phagocytosis
  • It suggests a deficiency in superoxide production
  • It rules out a defect in the ubiquitin-proteasomal pathway

    • What is the likely cause of the infant's omphalitis?

  • Impaired migration of leukocytes to the site of infection (correct)
  • Impaired opsonization of bacterial pathogens
  • An abnormality in the ubiquitin-proteasomal pathway
  • Defective production of reactive oxygen species

    • What is the classification of the genetic defect in leukocyte adhesion deficiency?

    <p>Autosomal recessive</p> Signup and view all the answers

    What is the role of CD18 (LFA-1) in leukocyte function?

    <p>Adhesion to endothelial cells</p> Signup and view all the answers

    Which of the following is NOT a feature of leukocyte adhesion deficiency?

    <p>Elevated immunoglobulin E levels</p> Signup and view all the answers

    What is the likely consequence of a defect in superoxide production?

    <p>Impaired killing of bacterial pathogens</p> Signup and view all the answers

    Which of the following is a complication of leukocyte adhesion deficiency?

    <p>Omphalitis</p> Signup and view all the answers

    What is the function of C5a in the complement system?

    <p>Neutrophil chemotaxis and histamine release from mast cells</p> Signup and view all the answers

    What is the function of LFA-1 (CD11a/CD18) in neutrophils?

    <p>Tight adhesion</p> Signup and view all the answers

    What is the result of a defect in the LYST gene?

    <p>Chediak-Higashi Syndrome</p> Signup and view all the answers

    Which cytokine is secreted by Th1 cells and activates macrophages to increase the inflammatory response?

    <p>IFN-γ</p> Signup and view all the answers

    What is the result of a defect in CD18?

    <p>Leukocyte adhesion deficiency type 1</p> Signup and view all the answers

    What is the function of PECAM-1 (CD31) in neutrophils?

    <p>Transmigration</p> Signup and view all the answers

    What is the function of C3b in the complement system?

    <p>Opsonization</p> Signup and view all the answers

    What is the result of a defect in the LFA-1 (CD18) adhesion molecule?

    <p>Leukocyte adhesion deficiency type 1</p> Signup and view all the answers

    What is the function of CD14 in the recognition of LPS?

    <p>Co-receptor for TLR4</p> Signup and view all the answers

    What is the result of a granuloma?

    <p>Chronic inflammation</p> Signup and view all the answers

    What is the primary function of Toll-Like Receptors (TLRs)?

    <p>To recognize and respond to pathogens and damaged cells</p> Signup and view all the answers

    What is the result of Leukocyte Adhesion Deficiency?

    <p>Impaired neutrophil migration</p> Signup and view all the answers

    Which of the following is NOT a component of the acute inflammatory response?

    <p>Granulomas</p> Signup and view all the answers

    What is the role of Hageman Factor XII in the inflammatory response?

    <p>Activation of bradykinin</p> Signup and view all the answers

    What is the primary characteristic of chronic inflammatory response?

    <p>Formation of granulomas</p> Signup and view all the answers

    What is the result of Chediak-Higashi Syndrome?

    <p>Defective lysosomal function</p> Signup and view all the answers

    Study Notes

    Physical Examination

    • Tenderness and erythema at the umbilical stump with serosanguinous drainage
    • Umbilical cord remains attached from birth
    • Induration along the surrounding tissues
    • Bulging right tympanic membrane with opacification and loss of light reflex

    Laboratory Evaluation

    • Hemoglobin: 16.5 g/dL
    • Leukocyte count: 45,500/mm3
    • Platelet count: 185,000/mm3
    • C-reactive protein: Elevated
    • Nitroblue tetrazolium dye reduction test: Positive

    Inflammatory Response

    • Toll-Like Receptors (TLRs) recognize PAMPs and DAMPs, triggering an inflammatory response
    • Arachidonic acid: lipooxygenase pathway à leukotrienes à ↑ neutrophil chemotaxis
    • Bradykinin, Hageman Factor XII: ↑ vasodilation, vascular permeability, and pain sensitivity
    • Inflammatory cytokines: IL-1, TNF-⍺, IL-6 à acute inflammatory process
    • Damaged endothelial cells: ↑ nitric oxide à ↑ vasodilation

    Neutrophil Migration

    • Margination: ↑ vascular permeability à hemoconcentration à ↑ neutrophil contact with endothelium
    • Rolling: Neutrophil: Sialyl LewisX; Endothelium: E-selectin, P-selectin
    • Tight Adhesion: Neutrophil: LFA-1 (CD11a/CD18), Mac1 (CD11b/CD18); Endothelium: ICAM-1 (CD54)
    • Transmigration: Neutrophil: PECAM-1 (CD31); Endothelium: PECAM-1 (CD31); driven by chemotaxis (LTB4, IL-8, C5a)

    Disorders of Leukocyte Migration

    • Leukocyte Adhesion Deficiency (LAD): absence of LFA-1 (CD18) à impaired tight adhesion
    • Chediak-Higashi Syndrome: impaired microtubule polymerization à ↓ neutrophil chemotaxis; LYST gene defect

    Chronic Inflammation

    • Fibrosis and angiogenesis
    • Granulomas: maintained by IL-12 and TNF-⍺; composed of multinucleated giant cells, fibroblasts, lymphocytes, and epithelioid cells

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