WK-3-Lec 9- PATHOLOGY OF TB

Question 1

What are the first cells to arrive at the infection site and help prevent early mycobacterial blood dissemination?

Answer 1

Neutrophils

Question 2

What is the stuff secreted by neutrophils upon arrival to the infection site to aid healing?

Answer 2

antimicrobials and proteases

Question 3

What does Phagocytosis of apoptotic neutrophils and granules by macrophages results to, which cease MT dissemination?

Answer 3

decreased viability of intracellular M.
Tuberculosis.

Question 4

Discuss the events that occur during pathogenesis of TB from MT inhalation to TB disease

Answer 4

• Inhalation of the mycobacteria is followed by its interaction with resident macrophages through cellular receptors and its internalization.
• Macrophage bactericidal mechanisms are then
  activated, including RNI and ROI generation
• Inflammatory cell recruitment: survived mycobacteria proliferate within macrophages inducing the production of proinflammatory cytokines.
• The local inflammatory environment induces the recruitment of several cell types including monocytes, neutrophils, and dendritic
  cells to the site of infection.
• Control of mycobacteria
  proliferation: arrival of immune cells to the site of infection including T cells, which become organized in characteristic structures called
  granulomas efficiently stop mycobacteria proliferation and contain the mycobacteria within the granuloma walls preventing its spread

-

Question 4

What are the 4 roles of Th1 in the fight against pulmonary TB?

Answer 4

Produces INF gamma, which:

• Causes fusion of phago- and lysosome –creates an acidic bactericidal environment
• Stimulates expression of inducible nitrous oxide synthetase (iNOS) which bacteria.
• Stimulates macrophage to produce TNF which recruits
  monocytes, epitheloid histocytes»to aid granuloma formation

Question 5

What is the characteristic of a ganuloma?

Answer 5

Foam cells

*Resulting from the differentiation of chronically activated macrophages

Question 6

How is Th1 introduced to the fight against pulmonary TB?

Answer 6

Bacterial antigens that drain into lymph nodes (were carried by immune cells- dendritic cells) stimulate a TH1 response, which activates macrophages and enhances their ability to kill bacteria.

Question 7

What are the features of Primary complex/Ghon Complex?

Answer 7

• subpleural location; 1-2 cm in size
• base of upper lobe
• or apex of lower lobe

Question 8

What are the 2 forms of post-primary TB?

Answer 8

1. Re-activation – of bacilli from previous infection.
   – usually lying dormant in areas of high o2 tension (lung
   apices/renal cortex, meninges
2. Re-infection – after a previous infection has healed

Question 9

What is seen with post primary infections? What do they show?

Answer 9

• caseating granulomas + fibrosis and cavitation
  – Apices upper lobe, superior segments lower lobes
  – Heal by fibrosis
  – usually little or no lymph involvement