Inflammation

Question 1

What two mechanisms do neutrophils use to kill microbes?

Answer 1

(1) Oxygen-dependent mechanisms are the most important. They involve generation of superoxide O2-via the NADPH system; this gives rise eventually to H2O2 and OH-. Also generated are myeloperoxidase-dependent HOCl radicals.
(2) Oxygen-independent mechanisms include lysozyme, lactoferrin, and defensins.

Question 2

Name any defects in neutrophil-killing mechanisms

Answer 2

Three important defects are

(1) defects in adhesion owing to genetic deficiency of β2 integrins (LAD-1);
(2) defects in chemotaxis or phagocytosis from an inherited impairment in assembly of microtubules (e.g., Chediak-Higashi syndrome); and
(3) defects in microbicidal activity owing to a genetic deficiency of the NADPH oxidase system (called chronic granulomatous disease) or genetic deficiency of myeloperoxidase.

Question 3

What factors (5) are secreted by activated macrophages?

Answer 3

(1) enzymes such as acid and neutral proteases, which cause tissue damage; (2) plasma proteins such as complement components and coagulation factors; (3) reactive oxygen species and nitric oxide;
(4) arachidonic acid
5) cytokines (e.g., interleukin-1 [IL-1], tumor necrosis factor [TNF], and growth factors such as FGF, EGF, and PDGF).

Question 4

What is the meaning of the term mononuclear infiltrate (often used to contrast with polymorphonuclear infiltrate)?

Answer 4

Mononuclear infiltrate refers to the presence of monocytes, plasma cells, and lymphocytes.

Question 5

The principal antigen-presenting cells in the epidermis

Answer 5

Langerhans cells

Question 6

What is granulation tissue?

Answer 6

Granulation tissue contains new small blood vessels, fibroblasts, and mononuclear cells in an edematous extracellular matrix; it is part of the repair response

Question 7

What is a granuloma?

Answer 7

A granuloma is a circumscribed collection of epithelioid cells, usually surrounded by lymphocytes; it is a particular form of chronic inflammation.

Question 8

What are the causes of caseous necrosis?

Answer 8

TB
Leprosy
Fungal infections

Question 9

What are the causes of granulomatous inflammation?

Answer 9

Causes are:

(1) bacterial (e.g., Mycobacterium tuberculosis, M. leprae, Treponema pallidum), (2) parasitic (e.g., schistosomiasis),
(3) fungal (e.g., histoplasmosis, blastomycosis),
(4) inorganic dusts (e.g., silicosis, berylliosis),
(5) foreign body, and
(6) Idiopathic/immune-related (e.g., sarcoidosis, Crohn disease).

Question 10

What is a granuloma?

Answer 10

A focal collection of epithelioid cells is called a granuloma.

Question 11

How are giant cells formed in granulomas?

Answer 11

Giant cells are formed by fusion of macrophages.