22 Questions
What is the primary cause of type III hypersensitivity reactions?
Formation of immune complexes in the blood or tissues
Which statement accurately describes the pathophysiology of type III reactions?
Immune complexes form and deposit in tissues, triggering chemotaxis of neutrophils and macrophages.
What role do complement factors C3a and C5a play in type III hypersensitivity reactions?
Promote chemotaxis of immune cells to the site of immune complex deposition
Which factor deficiency can reduce clearance of immune complexes and increase susceptibility to type III reactions?
Factor I deficiency
In type III hypersensitivity, where do immune complexes deposit if they are not cleared from circulation?
Joint tissue
What is the main consequence of complement activation in type III hypersensitivity reactions?
'Frustrated phagocytosis' and inflammation leading to tissue damage
What is the predominant T cell response in granulomatous hypersensitivity?
CD4+ Th1 cell response
Which cells are recruited to the site of chronic infection in granulomatous hypersensitivity?
Th1 cells
What triggers airway macrophages to penetrate into the underlying tissue in granulomatous hypersensitivity?
TLR engagement
Which cytokines are released by macrophages in granulomatous hypersensitivity to promote vasodilation and endothelial adhesion molecule expression?
IL-1β, IL-6, and TNF-α
What is a characteristic of immune complex deposition in Type III hypersensitivity reactions?
Deposition of antigen-antibody complexes
How do T regulatory (Treg) cells aid in the resolution of the inflammatory response?
By suppressing the inflammatory response
What triggers the activation of phagocytes by binding to Fc receptors and complement receptors?
IC and C3b
Which factor may induce peptidyl arginine deiminases (PAD) activity to generate self-antigens for Rheumatoid Arthritis?
Smoking
In Rheumatoid Arthritis, what is the role of Rheumatoid Factor (RF)?
Serves as an indicator of inflammatory and autoimmune activity
What is the significance of HLA-DR4 in Rheumatoid Arthritis?
Good at presenting citrullinated self-Antigens
Which disease is characterized by the formation of immune complexes that deposit in tissues, leading to type III hypersensitivity reactions?
Systemic Lupus Erythematosus
In Systemic Lupus Erythematosus, what leads to chronic disease setting and eventual tissue destruction?
Epitope spreading
What process in SLE results in the production of broad Ig responses against various self-antigens?
Isotype switching of GC B cells
What is the key factor that leads to T cell activation and epitope spreading in Systemic Lupus Erythematosus?
Defective apoptotic body clearance
Which cells are primarily involved in capturing haptenated proteins during the sensitization stage of Contact Hypersensitivity?
Langerhans cells and cutaneous dendritic cells
What is the effect of Fas ligand engagement with Fas in Contact Hypersensitivity?
Induces apoptosis of keratinocytes
Explore the concepts of type III and IV hypersensitivity reactions in this quiz from the PBC 9700 Session 12 course by Randal K. Gregg, PhD. Learn about antigens, genetic predispositions, cytokines, antibody isotypes, effector mechanisms, associated diseases, and immune complex definitions and removal mechanisms.
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