58. Tuberculum. Predominantly exudative and predominantly proliferative tuberculosis

Question 1

What bacteria causes tuberculosis?

Answer 1

Mycobacterium bovis/tuberculosis/avium

Question 2

Properties of bacteria causing tuberculosis?

Answer 2

Gram+, ZIEHL-NEELSEN+ (!)
acid and alcohol fast coccoid RODS
Very resistant cell wall (mycolic acid and wax-like substances)

Question 3

What does acid fast bacteria mean?

Answer 3

bacteria is resistant to decolorization by acids during laboratory staining procedures. (that’s why mycobacterium stays pink in ziehl-neelsen staining)

Question 4

Ziehl-Neelsen stain

Answer 4

Use to stain Acid-fast bacteria (Nocardia, Mycobacterium). These bacteria stay pink

Question 5

Does Mycobacteria live intracellularly or extracellularly?

Answer 5

Intracellularly and replicate also IC (in macrophages)

Question 6

What cells do mycobacteria enter? How?

Answer 6

Macrophages. By receptor-mediated endocytosis

Question 7

Why macrophages are not able to kill mycobacteria?

Answer 7

Mycobacteria blocks the fusion of phagosome and lysosome. Mycobacteria replicates inside of macrophages (primary tuberculosis)

Question 8

Sensitization phase?

Answer 8

Approx 3 weeks after infection IL-12 is produced by antigen presenting cells (macrophages, dendritic cells) after activation of toll-like receptors 2 (TLR-2) -> activation of Th1 response (T-helper cells)

Question 9

What cells produce IL-12?

Answer 9

infected macrophages and dendritic cells. (Activation of TLR-2)

Question 10

What cells produce IL-2?

Answer 10

Th1 cells. Leads to proliferation of Th1 and other lymphocyte cells. EFFECTOR PHASE

Question 11

Th1 response is activated by …?

Answer 11

by cytokines including IL-12 (from infected macrophages and dendritic cells) and INF-gamma (from NK-cells and Th1 cells)

Question 12

Th1 response

Answer 12

• secretion of INF-gamma ->
  1. reinforcing Th1 cells production
  2. activation of macrophages
• secretion of IL-2 -> proliferation of lymphocytes

can sometimes lead to autoimmune reactions

Question 13

What cells produce interferon gamma?

Answer 13

NK-cells (?), Th1 cells

Question 14

Effect of INF-gamma on macrophages - ?

Answer 14

boosts macrophages’ ability to kill IC pathogens by increasing their production of ROS, nitric oxide and lysosomal proteases

Question 15

What do activated macrophages release? What happens to them?

Answer 15

TNF-alpha and IL-1 that will further activate cells and immune system. Epitheloid cells (macrophages will fuse and form Langhans giant cells

Question 16

epitheloid cells

Answer 16

activated macrophages that resemble epithelial cells. May fuse and form Langhans giant cells

Question 17

Langhans giant cells

Answer 17

Fused epithelioid cells in tuberculosis, present in granulomas

Question 18

What type of necrosis happens in tuberculosis?

Answer 18

Caseous (cheese-like)

Question 19

What changes can be noticed if animal is slaughtered 7/14/21/35 days after infection?

Answer 19

7 days: intraalveolar macrophages, giant cells, neutrophils
14 days: in the tubercles central neutrophil aggregates surrounded by epitheloid cells
21: central necrosis in the tubercles
35: first mineralized lesions (Ca++ deposition)

Question 20

Why X-ray in tuberculosis?

Answer 20

Variable degree of calcification in the necrosis layer of tuberculum may be seen on X-ray

Question 21

What are layers of tubercel (inside-outside)

Answer 21

necrosis - macrophages - capsule containing lymphocytes and collagenous connective tissue with fibrocytes

Question 22

Tuberculous cold abscess

Answer 22

Pyogenic bacteria

Question 23

Tuberculous caverns

Answer 23

histolysis followed by discharge via airways

Question 24

Miliary tuberculosis

Answer 24

Multiple small sized lesions

Question 25

How is merging of several tubercles called?

Answer 25

Conglomerate of tubercles

Question 26

Morphology of tuberculosis in birds

Answer 26

Lack of central calcification. Foreign body granuloma type. Necrotic area is surrounded by foreign body giant cells radially -> palisade formation

Question 27

Predominantly proliferative tuberculosis - ? Why this happens?

Answer 27

Lack of Th1 type response -> no central necrosis -> no granuloma formation. Proliferation of tuberculous granulation tissue.

Question 28

Morphology of proliferative tuberculosis ?

Answer 28

No necrosis, no calcification. No foci (no tuberculum) but larger, tumor-like (fibrosarcoma) lesions: greyish, homogenous, infiltrative lesion, no sharp demarcation

Question 29

What species often has proliferative tuberculosis?

Answer 29

Pigs, liver

Question 30

Predominantly exudative tuberculosis - ?

Answer 30

Severe exudation. Fibrinogen rich exudate. No cellular reaction. Coagulation, necrosis, caseation -> demarcation