Pulmonary Host Defense

Question 1

4 ways that the mechanical protection of the upper airway can be impaired?

Answer 1

Altered consciousness. (esp. aspiration)
Laryngeal dysfunction.
Intubation / tracheostomy. (allows microbes deep into lungs)
Altered adhesive properties of resp. mucosa.

Question 2

3 aspects of mechanical protection in the lower conducting airways?

Answer 2

Bronchial branching -> turbulent flow -> better particle trapping.
Mucus.
Cilia.

Question 3

What can happen if you chronically suppress coughing?

Answer 3

Recurrent right middle lobe infections..

Coughing’s important.

Question 4

Things that impair the bronchial branching mechanical protection of the lower airways?

Answer 4

CF -> diffuse bronchiectasis (dilation)

Post-pneumonia, TB, pertussis -> focal bronchiectasis

Question 5

Typical cause defects in mucous protection?

Answer 5

CF

Question 6

Common causes of airway clearance defects?

Answer 6

Tumors, foreign bodies blocking airway.

Voluntary cough suppression.

Question 7

What fails to happen in CF, leading to defective lower airway defenses?

Answer 7

Impaired Cl- secretion -> impaired water secretion -> ciliary defect.
Also, defensins aren’t secreted due to osmotic defects.

Question 8

How does cavitary TB, even if treated, predispose to future infections?

Answer 8

Old cavities don’t get drained well, so can be invaded by things like aspergillus.

Question 9

Epithelial cells in the airway have TLRs and secrete innate defense moecules.

Answer 9

Good.

Question 10

What does neutropenia particularly predispose to?

Answer 10

Gram negative pneumonia and invasive aspergillosis.

Question 11

2 causes of desquamated / injured respiratory epithelium?

What does this predispose to particularly?

Answer 11

Airway burns / smoke inhalation, post-influenza.

Causes susceptibility to bacterial pneumonia, esp. Strep pneumo and Staph.

Question 12

Collectins, complement, and things like transferrin are important.

Answer 12

Yeah.

If you’re complement deficient, one has recurrent pyogenic infections with encapsulated organisms.

Question 13

What organisms are Abs / B cells most important for controlling?
Which organ is very important for clearing these opsonized organisms?

Answer 13

Encapsulated bacteria (S. pneumo, H. flu, meningococcus).
The spleen is particularly important - sickle cells pts with functional asplenia are predisposed to these.

Question 14

5 acquired causes of Ab dysfunction?

quantitative or functional?

Answer 14

Multiple myeloma (quantitative and functional).
Nephrotic syndrome (quantitative).
Sickle cell (functional and asplenia).
Asplenia (functional).
AIDS (functional, though there's often an ineffective hypergammaglobulinemia).

Question 15

3 common causes of cell-mediated immune defects?

Answer 15

AIDS, corticosteroids, immunosuppression.

Question 16

3 common fungal lung infections seen in cell-mediated immune deficiency?

Answer 16

Pneumocystis jiroveci (PCP).
Histoplasmosis.
Cryptococcus.

Question 17

2 viral lung infection that commonly seen in cell-mediated immune deficiency?

Answer 17

CMV, Kaposi’s sarcoma (HHV-8).

Question 18

3 bacterial lung infections commonly seen in cell-mediated immune deficiency?

Answer 18

TB.
Mycobacterium avium.
Nocardia. (first time I’ve heard of this one…)

Question 19

Must an infection in a patient with an immunodeficiency get be caused by an opportunistic organism?

Answer 19

Of course not. Just because the boards questions will be structured as such, immunosuppressed people still get infections with S. pneumo, and it’s worse.

Question 20

Typical, non-immunocompromised presentation of lung TB?

Answer 20

Upper lobe, cavitary.

Question 21

Atypical patterns of TB that can be seen in immunocompromised patients?

Answer 21

Non-cavitary, lower lobe, adenopathy only, milliary (disseminated), extrapulmonary.

Question 22

Review: what do you seen in TB histology?

Answer 22

Acid fast bacilli.

Granulomas with giant cells (assuming CD4’s intact enough to do this).

Question 23

Only people who are extremely immunocompromised get M. avium and CMV in the lungs.

Answer 23

Okay.