Examkin

Soru

Zorluk: ZorImmunologic and Inflammatory Processes

A pediatric immunology clinic evaluates several patients with suspected primary immunodeficiencies. For each patient profile below, identify the primary immunopathologic mechanism responsible for their disease.

  • A 4-week-old infant with a leukocyte count of 55,000/mm³ (85% neutrophils), delayed umbilical cord separation, and necrotic, non-purulent omphalitis.Absent beta-2 integrin (CD18) expression impairing neutrophil adhesion and transmigration
  • An 8-month-old infant with a history of Serratia marcescens osteomyelitis whose dihydrorhodamine 123 flow cytometry assay demonstrates no fluorescent shift.Defective phagocyte NADPH oxidase complex preventing reactive oxygen species generation
  • A 3-year-old child presenting with severe eczema, recurrent encapsulated bacterial pneumonias, and a platelet count of 35,000/mm³ with notably small platelets.Mutated cytoskeletal regulatory protein leading to defective actin polymerization in hematopoietic cells
  • A 16-year-old adolescent with normal immunoglobulin levels and T-cell counts who is recovering from a second episode of meningococcal bacteremia.Deficiency of late complement components (C5-C9) preventing membrane attack complex formation
  • A 7-month-old infant with recurrent Giardia lamblia infections, physical examination revealing absent tonsillar tissue, and profoundly decreased serum IgA, IgG, and IgM.Mutated cytoplasmic Bruton tyrosine kinase causing failure of pre-B cells to mature into B cells

Cevap

Patient 1 matches with absent beta-2 integrin (CD18). Patient 2 matches with defective NADPH oxidase. Patient 3 matches with mutated cytoskeletal regulatory protein (actin). Patient 4 matches with deficiency of late complement components. Patient 5 matches with mutated Bruton tyrosine kinase.
Each primary immunodeficiency presents with a unique pattern of infections and laboratory findings directly tied to its underlying molecular defect. Accurately diagnosing these conditions requires linking the specific clinical phenotype (e.g., small platelets, absent tonsils, Neisseria susceptibility) to the disrupted step in the immunologic cascade.

Adım Adım Çözüm

1
Analyze Patient 1's presentation
Identified Leukocyte Adhesion Deficiency Type 1 (LAD-1)
The triad of delayed cord separation, lack of pus (omphalitis without purulence), and extreme neutrophilia indicates neutrophils cannot exit the bloodstream, linked to CD18 integrin defects.
2
Analyze Patient 2's presentation
Identified Chronic Granulomatous Disease (CGD)
Serratia (catalase-positive) infection and a negative dihydrorhodamine (DHR) flow cytometry test confirm an inability of phagocytes to generate reactive oxygen species via NADPH oxidase.
3
Analyze Patient 3's presentation
Identified Wiskott-Aldrich Syndrome (WAS)
The combination of eczema, recurrent infections, and specifically microthrombocytopenia (small platelets) is pathognomonic for WAS, caused by an actin cytoskeleton defect.
4
Analyze Patient 4's presentation
Identified Terminal Complement Deficiency
Recurrent Neisserial infections in a patient with otherwise normal T and B cell function point to a defect in the late complement cascade (C5-C9) which forms the Membrane Attack Complex.
5
Analyze Patient 5's presentation
Identified X-linked Agammaglobulinemia (XLA)
Absent tonsils and pan-hypogammaglobulinemia with recurrent Giardia indicate a failure of B-cell development, driven by mutated Bruton tyrosine kinase (BTK).

Anahtar Kavram

Pathophysiology and molecular mechanisms of Primary Immunodeficiency Syndromes
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Konular

Immunologic and Inflammatory Processes

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