Innate Immunity

Question 1

Describe the key differences between the innate and adaptive immune systems.

Answer 1

Innate: handles 95% of antigens, non-specific, occurs immediately

Adaptive: handles 5% of antigens, specific, variable lag periods

Question 2

What are the three lines of defense?

Answer 2

First: Innate, physical and chemical barriers
Second: Innate, cellular defense
Third: Adaptive, cellular (cytotoxic) and humoral (antibodies)

Question 3

The skin, G.I. system, respiratory system, urogenital system, and mammary glands are what type of barriers?

Answer 3

Physical (first line)

Question 4

Lysozymes, complement c’, lysins, chemokines, opsonins, and acute phase proteins are what type of barriers?

Answer 4

Chemical (first line)

Question 5

Describe ways the the skin acts as a physical barrier.

Answer 5

• contains sebaceous glands that contain acidic sebum, which degrades antigens
• natural intactness/durability
• microbiome/non-pathogenic bacteria on the surface compete against pathogens and produce antimicrobial peptides

Question 6

What roles does saliva play as a physical barrier?

Answer 6

Flushing action of pathogens; lysozymes

Question 7

What are lysozymes?

Answer 7

A naturally occurring enzyme found in bodily secretions (tears, saliva, sweat) and in the G.I. tract that has antimicrobial factors (cleaves bacterial cell walls –> cell death)

Question 8

How does urine act as a physical barrier?

Answer 8

Flushing action; low-pH environment kills pathogens

Question 9

What is the vagina’s epithelium rich in that allows it to serve as a physical barrier?

Answer 9

Glycogen, which promotes the growth of “Lactobacillus” => lactic acid –> antimicrobial

Question 10

What is the significance of the trachea being lined by mucous with regard to the respiratory tract’s role as a physical barrier?

Answer 10

Goblet cells produce mucous –> mucous secretes lysozymes on trachea lining. Ciliary lining of trachea push pathogen-containing mucous out of body (i.e., coughing)

Question 11

What are lectins and why are they significant for the mammary glands’ role as a physical barrier?

Answer 11

Lectins are proteins within mammary glands that act as receptors for lactoferrin, an iron-binding glycoprotein. Lactoferrin decreases the availability of iron; invading pathogens must be bound to iron in order to multiply

Question 12

What are complement (C’) proteins and their roles as a chemical barrier? Where are they produced in the body?

Answer 12

C’ proteins work together to opsonize foreign pathogens and induce phagocytosis; are ubiquitous in the body because infection can occur anywhere (produced by: parenchyma of liver, macrophages, monocytes, GI/urinary tracts, etc.)

Question 13

Describe the chemotaxis function of c’ proteins.

Answer 13

C’ proteins attract/recruit neutrophils and macrophages to site of antigen for phagocytosis

Question 14

What 2 C’ proteins are critical for maintaining the immune system, regulating inflammation and eliminating antigens?

Answer 14

C3 and C5

Question 15

Describe the opsonization process of the complement system.

Answer 15

E.g., C3 is cleaved –> C3b. C3b binds to antigen; the recruited macrophage has a receptor site for C3b –> phagocytosis of antigen (and C3b).