MLT GlobeBasic Pathology: Inflammation – page 5
134 Basic Pathology MCQs on Inflammation with answers and explanations.
In severe sepsis, which macrophage cytokine is the principal driver of hypotension, and with chronic production causes cachexia?
TNF activates endothelium and, at high systemic levels, causes vasodilation, reduced cardiac output and shock; chronic TNF causes cachexia. IL-2 and IL-4 are T-cell cytokines.
Plasma-derived precursors of inflammatory mediators are converted to their active forms mainly:
Circulating inactive precursors such as complement and kininogens are activated locally at the inflamed site, so their effects stay focused.
Which inflammatory mediator is NOT produced by mast cells?
Bradykinin comes from plasma kininogen through the kallikrein system. Mast cells release histamine and synthesize prostaglandins, leukotrienes and PAF.
Which prostaglandin mediates fever during infection and sensitizes the skin to painful stimuli?
PGE2 acts on the hypothalamus to cause fever and makes pain receptors hypersensitive (hyperalgesia). PGI2 is a vasodilator and platelet inhibitor.
Which arachidonic acid metabolite causes vasoconstriction rather than vasodilation?
Thromboxane A2 from platelets is a vasoconstrictor and platelet aggregator. PGI2, PGE2 and PGD2 are vasodilators.
Bacterial surface components can trigger the intrinsic coagulation pathway directly by activating which factor?
Factor XII is activated by contact with negatively charged surfaces, including microbial components, linking inflammation with clotting and kinin generation.
Which pair of specific gravity values correctly separates an exudate from a transudate?
Exudates are rich in protein and cells, giving specific gravity above 1.020. Transudates are protein-poor with specific gravity below 1.012.
Which mediator is principally responsible for the immediate transient leakage produced by endothelial gaps in postcapillary venules?
Histamine causes rapid endothelial contraction in venules within minutes, lasting 15-30 minutes. Cytokines cause slower, longer-lasting retraction.
Which nitric oxide synthase isoform is induced in macrophages by cytokines such as IFN-gamma and produces NO for killing microbes?
iNOS is not normally present but is induced in activated macrophages, generating large amounts of NO that combines with superoxide to kill microbes.
Within neutrophils, which enzyme converts hydrogen peroxide and chloride into hypochlorite, a potent microbicidal agent?
Myeloperoxidase from azurophilic granules produces HOCl from H2O2 and Cl-. NADPH oxidase produces superoxide, and SOD converts superoxide to H2O2.
Phagocyte oxidase oxidizes NADPH and, in doing so, reduces molecular oxygen to:
NADPH oxidase adds one electron to O2 to form superoxide anion, which becomes H2O2 and then hypochlorite via myeloperoxidase.
Which phagocyte receptors bind oxidized LDL as well as many microbes, contributing to foam cell formation?
Scavenger receptors on macrophages ingest modified LDL and various microbes. Mannose receptors recognize terminal mannose and fucose residues.
Which phagocyte lectin receptor recognizes terminal mannose and fucose residues typical of microbial, but not host, glycoproteins?
The mannose receptor binds terminal mannose and fucose sugars common on microbial walls; host glycoproteins end in sialic acid or galactosamine, so they are ignored.
Neutrophils dominate the first 6-24 hours of acute inflammation. Which of the following is NOT a reason for this?
Neutrophils predominate early because they are abundant, respond quickly to chemokines and attach readily to adhesion molecules. They are short-lived in tissue, being replaced by longer-lived macrophages.
Which complement fragment is NOT an anaphylatoxin?
C3a, C4a and C5a stimulate mast cell histamine release and are called anaphylatoxins. C3b is an opsonin that promotes phagocytosis.
In acute inflammation, early neutrophils are replaced by monocyte-derived macrophages over approximately:
Neutrophils predominate at 6-24 hours; they die by apoptosis and are replaced by macrophages over 24-48 hours.
Viral infections often show a lymphocyte-rich infiltrate from the start rather than neutrophils. What explains this?
The cell composition of an infiltrate depends on the stimulus and the age of the response. Viral infections, for example, attract lymphocytes first.
Which statement about tumor necrosis factor is INCORRECT?
TNF is a cell-derived cytokine from macrophages, mast cells and other cells. It is not a plasma protein precursor like complement or kininogen.
Chemokines and other chemoattractants act on leukocytes by binding to which receptor type?
Chemoattractant receptors (for chemokines, C5a, LTB4, bacterial peptides) are seven-transmembrane G-protein-coupled receptors that drive actin polymerization and movement.
Which lipoxygenase product of arachidonic acid is a powerful chemoattractant for neutrophils?
LTB4 is a potent chemotactic agent. LTC4 and LTD4 cause vasoconstriction, bronchospasm and increased permeability; PGI2 is a cyclooxygenase product.