Immune Deficiency and Defense

Question 1

Immunodeficiency results in the increased incidence of what three things?

Answer 1

• Infections
• Malignancy
• Autoimmunity (because of decreased regulatory function)

Question 2

What is a normal incidence of infectious disease in a healthy child?

Answer 2

• Birth to age 10: 6-8 URIs per year

* First three years: less than 7 episodes of OM; 2 episodes of gastroenteritis per year

Question 3

What are some clues to immunodeficiency?

Answer 3

• Recurrent infections
• Severe infections
• Prolonged illnesses
• Increased frequency of illness
• Unusual pathogens

Question 4

Describe the difference between public and private phenotypes.

Answer 4

Private phenotypes are immunodeficiencies that only predispose the person to a narrow range of disorders (DiGeorge), and public phenotypes are immunodeficiencies that predispose people to broad categories of disorders (e.g., SCID).

Question 5

The most common cause of immunodeficiency worldwide is ______________.

Answer 5

malnutrition

Question 6

Next to malnutrition, the top causes of immunodeficiency are _____________.

Answer 6

HIV, age, measles, and immunosuppressive medications

Question 7

What can compromise the anatomic barriers that serve to protect the body from infection?

Answer 7

• Skin: burns, eczema, IVs
• Lung: CF, post viral illness
• GI tract: chemotherapy

Question 8

What bugs are most commonly implicated in pneumonia in young people, elderly people, those with AIDS, and hospital infections?

Answer 8

• Young people: S. pneumoniae, C. pneumoniae, and M. pneumoniae
• Elderly: H. influenzae, Influenza, and S. pneumoniae
• AIDS: Pneumocystis jirovecii and S. pneumoniae
• Nosocomial: Gram-negative rods and S. aureus

Question 9

Which infections are more likely in those with antibody deficiency?

Answer 9

Encapsulated organisms, enterovirus, and Giardia lamblia

Question 10

Why do those with multiple myeloma have immune deficiency?

Answer 10

The malignant plasma cells crowd out all other plasma cells. People with MM effectively have only one kind of antibody.

Question 11

Which (pretty serious) immunodeficiency disorder can arise in adulthood?

Answer 11

Common-variable immune deficiency (CVID)

This presents with absence of immunoglobulin.

Question 12

Normal CD4 counts are ______________.

Answer 12

500 –1,500

Question 13

What do the subtypes of IgG recognize?

Answer 13

IgG1: protein (more prevalent)
IgG2: polysaccharide

Question 14

Describe CVID.

Answer 14

• Presents in adulthood (20s)
• Symptoms include recurrent sinusitis, GI infection, or pneumonia
• Decreased levels of IgG, IgM, and IgA with normal levels of B cells and T cells
• Increased risk of malignancy (NHL and gastric cancers)
• Splenomegaly

Question 15

_______________ release antimicrobial agents when they bind the Fc receptor.

Answer 15

NK cells

Question 16

Worldwide, how many new HIV infections occur each year?

Answer 16

2 million

Question 17

What organisms are those with CGD more susceptible to?

Answer 17

Catalase-positive organisms: 
•Staphylococcus aureus
•Pseudomonas aeruginosa
•Serratia
• Nocardia
•Aspergillus 
•Salmonella

Question 18

By CD4 count, what defines “advanced AIDS”?

Answer 18

Less than 200 cells /uL