40 Questions
What is the primary function of the innate immune response?
To respond rapidly to microbes or damage
Which process is involved in eliminating pathogens as part of the innate immune response?
Phagocytosis
What is the role of cytokines and chemokines in the innate immune response?
To act as an alarm system by signaling danger and attracting immune cells
How does the innate immune system communicate with the adaptive immune system?
Through antigen presentation
Which pathway is responsible for presenting antigens from viruses or intracellular bacteria?
MHC class I pathway
Which deficiency is associated with severe recurrent infections by Neisseria gonorrhoeae or Neisseria meningitidis?
Deficiency in terminal pathway (C5-C9)
Which immune complex-mediated autoimmune disease is associated with deficiency in early components (eg C2 and C4)?
Systemic lupus erythematosus
Which immune cell is responsible for antigen presentation in the MHC class II pathway?
Dendritic cell
Which cellular process is initiated by innate immune cell activation?
Phagocytosis
Which type of cells express MHC class I for antigen presentation?
All nucleated cells
Which plasma proteins are involved in the innate immune response in the blood?
Complement
Which process involves the constant presentation of self-peptides, cancer antigens, or antigens derived from viruses or intracellular bacteria?
MHC class I presentation
Which cells are responsible for initiating phagocytosis and inflammation in the tissues?
Resident macrophages, dendritic cells, and mast cells
Which cells are recruited from the blood to the site of infection as part of the innate immune response?
Neutrophils
Which cells travel from the site of infection to the lymph nodes for antigen presentation to T cells?
Dendritic cells
Which cells are involved in the presentation of pathogens, toxins, and fragments in the MHC class II pathway?
Antigen presenting cells (APCs)
Which process leads to the engulfment and killing of microorganisms by toxic substances like NO and ROS?
Phagocytosis
What causes Chronic Granulomatous Disease (CGD) when defective?
NADPH oxidase system
Which assay is used to diagnose Chronic Granulomatous Disease (CGD)?
Dihydrorhodamine (DHR) assay
What are the key signs of inflammation?
Redness, swelling, heat, and pain
What do innate immune cells recognize in microbes?
Pathogen-associated molecular patterns (PAMP)
What do innate immune cells express to recognize different pathogens?
Pathogen Recognition Receptors (PRR)
What does inflammation respond to?
Infection/insult/injury
What does the NADPH oxidase system produce to kill microorganisms?
Toxic substances like NO and ROS
What is the main function of Pathogen Recognition Receptors (PRR) on innate immune cells?
Recognize different pathogens
What is the process that leads to the release of histamine and causes redness, swelling, heat, and pain?
Extravasation
What is the result of innate immune cell activation?
Phagocytosis, cytokine production, and antigen presentation
What is the consequence of defects in the NADPH oxidase system?
Chronic Granulomatous Disease (CGD)
Which of the following is NOT a function of the complement system?
Triggering apoptosis of infected cells
What is the primary role of IL-8 in the inflammatory response?
Aiding leukocyte adhesion
Which of the following is NOT a mechanism for termination of inflammation?
Enhanced vasodilation
What is the primary function of C5b binding to C6-C9 in the complement system?
Triggering apoptosis of infected cells
Which of the following is NOT a role of chemokines in the inflammatory response?
Promoting vasodilation
What is the consequence of complement deficiencies?
Frequent bacterial infections
Which of the following is NOT a function of C3a and C5a fragments in the complement system?
Inhibiting phagocytosis
What is the role of IL-1 and TNF in the inflammatory response?
Causing endothelial cells to express selectin
Which cells are responsible for producing inflammatory mediators in the innate immune response?
Dendritic cells
What is the primary function of the three pathways that initiate the complement system?
Microbe opsonisation
What is the primary function of chemokines in the inflammatory response?
Recruiting neutrophils
Which of the following is NOT a role of the complement system?
Inhibiting leukocyte adhesion
Study Notes
Innate Immune Cell Activation and Inflammation
- Tissue injury can cause inflammation, recognized by innate immune cells
- Microbes have molecular patterns recognized by innate immune cells, termed 'pathogen-associated molecular patterns' (PAMP)
- Innate immune cells express receptors to recognize different pathogens, called 'Pathogen Recognition Receptors' (PRR)
- Innate immune cell activation leads to phagocytosis, cytokine production, and antigen presentation
- Phagocytosis engulfs and kills microorganisms by toxic substances like NO and ROS
- Defects in the NADPH oxidase system lead to Chronic Granulomatous Disease (CGD)
- CGD causes frequent and severe bacterial and fungal infections, diagnosed by the Dihydrorhodamine (DHR) assay
- Inflammation responds to infection/insult/injury, brings immune cells to fight it, localizes the infection, and increases production of protective proteins
- Key signs of inflammation include redness, swelling, heat, and pain
- Key stages of inflammation involve recognition via PRR, vasodilation, permeability, cell adhesion, and extravasation
- Activation of neutrophils and monocytes leads to phagocytosis, destruction of microbes, and release of more inflammatory mediators
- Extravasation involves the release of histamine and leads to redness, swelling, heat, and pain
Innate Immunity and the Complement System
- Innate immunity involves the release of cytokines (IL-1, TNF) and chemokine (IL-8) by macrophages upon microbe detection
- IL-1 and TNF cause endothelial cells to express selectin for rolling adhesion of leukocytes
- IL-8 on endothelial cells aids in leukocyte adhesion and leads to firm binding/arrest of rolling leukocytes
- Inflammatory mediators, such as vasodilators and permeabilisers, are produced by damaged epithelium, resident macrophages, dendritic cells, and mast cells
- Inflammatory cytokines and chemoattractants promote recruitment and sustained activation of immune cells
- Chemokines, like IL-8, are crucial in the inflammatory response for recruiting neutrophils to the infected region
- Termination of inflammation involves mechanisms like short half-life of neutrophils, macrophage character change, and lipid mediators
- Chronic inflammation of prolonged duration includes active inflammation, tissue injury, and healing simultaneously
- The complement system consists of plasma proteins that promote inflammation, opsonisation, phagocytosis, and microbe killing
- The complement system is initiated by three pathways and is a non-specific innate immune mechanism
- C3a and C5a fragments promote inflammation, act as chemoattractants, and enhance vasodilation and vascular permeability
- C3b is deposited on microbe surfaces, acts as an opsonin, and triggers phagocytosis; C5b binding to C6-C9 forms a membrane attack complex causing cell death and complement deficiencies are rare and linked with frequent bacterial infections
Test your knowledge of innate immune cell activation, inflammation, and the complement system with this quiz. Explore the recognition of pathogens, key inflammatory mediators, stages of inflammation, and the role of the complement system in promoting inflammation and microbe killing.
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