WBCs IN THE BLOOD
Name one white blood cell commonly found circulating in blood.
Neutrophil
Name one white blood cell that primarily functions in tissues.
Macrophage
What event activates the innate immune response?
Tissue damage or pathogen entry
Which cell releases histamine?
Mast cell
Name one non-cellular innate immune defence.
Complement proteins
Name 2 cells that have pattern recognition receptors
E.g. Macrophages, dendritic cells
What precursor cell differentiates into macrophages?
Monocytes
Which cells detect pathogens and release signalling molecules?
Macrophages / dendritic cells
What is the immediate effect of histamine release?
Vasodilation & increased capillary permeability
Which molecules are released by virus-infected cells?
Interferons
Why are neutrophils suited to circulating in blood?
Rapid mobility & short lifespan
Why do macrophages arrive later than neutrophils?
Slower migration but longer-lasting action
Why is the innate immune response considered non-specific?
Same response to all pathogens
Why does inflammation cause redness and swelling?
Increased blood flow & fluid leakage
Phagocytosis is the process which involves...
...the engulfment and destruction of a pathogen or cellular debris.
Upon detecting infection, monocytes can differentiate into macrophages or dendritic cells. Use an analogy to explain this.
Answer includes appropriate description:
Macrophages: Directly fight pathogens (e.g. frontline soldiers)
Dendritic cells: Coordinate the immune response (e.g.) intelligence officers
Evaluate the importance of macrophages in both pathogen removal and resolution of inflammation.
Remove pathogens, clear debris, release cytokines to regulate response
Justify why NK cells are critical in early viral infections despite lacking antigen specificity.
Act rapidly without prior exposure, limit viral spread
Predict and explain the consequences of excessive or prolonged histamine release.
Excessive swelling, tissue damage, allergic symptoms.
Compare opsonisation by complement proteins with antiviral action of interferons.
Opsonisation enhances phagocytosis of bacteria; interferons inhibit viral replication
A patient undergoes chemotherapy, causing severe neutropenia (reduction of neutrophils). Predict and justify the immediate and downstream effects on innate immune defence against bacteria.
(1) Reduced phagocytosis
(2) increased bacterial proliferation
(3) greater reliance on macrophages
(4) delayed clearance
Analyse how failure of macrophage-mediated cleanup would alter the resolution phase of inflammation and tissue repair.
(1) Persistent debris
(2) prolonged inflammation
(3) delayed healing
Evaluate why the innate immune system must respond rapidly but non-specifically, and explain the consequences if specificity were required.
(1) Speed prevents spread
(2) specificity would delay response and increase pathogen load
Excess histamine release occurs during an allergic reaction. Explain how this disrupts normal inflammatory control mechanisms.
(1) Excess permeability
(2) tissue damage
(3) impaired function
A bacterial pathogen lacks surface markers that bind complement efficiently. Predict how this affects opsonisation and phagocytosis.
(1) Reduced opsonisation
(2) decreased phagocyte recognition
(3) slower clearance