Module 3: Section 2E

Question 1

How does inflammation link innate and adaptive immunity?

Answer 1

• Inflammation warns the adaptive immune system about pathogens
• Cytokines and chemokines draw phagocytic cells to the infection site and activate them

Question 2

How do macrophages and dendritic cells bridge innate and adaptive responses?

Answer 2

They phagocytose pathogens, process microbial antigens, and present them to lymphocytes, starting the adaptive immune response

Question 3

What are lymphocytes and what do they become?

Answer 3

white blood cells that mature into B cells or T cells depending on their location

Question 4

What happens when B cells are exposed to an antigen?

Answer 4

• B cells make antigen-specific antibodies
• Some become Memory B cells that quickly produce antibodies during later infections

Question 5

What happens when T cells are exposed to an antigen?

Answer 5

• T cells form Memory T cells for future infections
• Can also form Cytotoxic T Lymphocytes (CTLs) that kill infected or cancerous cells

Question 6

Opsonization

Answer 6

• Binding of antibodies to the pathogen surface provides a ligand that binds to the macrophage membrane
• Greatly enhances the probability of engulfment

Question 7

Precipitation

Answer 7

• Antibodies have at least 2 antigen-binding sites and can therefore bind multiple antigens
• The binding of multiple soluble antigens forms large complexes that become insoluble and precipitate

Question 8

Neutralization

Answer 8

Neutralization happens when antibodies bind to pathogens or their toxins, blocking them from attaching to or entering host cells

Question 9

Complement fixation

Answer 9

• Antibody cross-linked pathogen complexes activate the complement system through the classical pathway
• causing cell lysis

Question 10

Agglutination

Answer 10

Antibodies have at least two antigen-binding sites, letting them bind multiple antigens and link pathogens into large complexes that are then phagocytosed

Question 11

Cytotoxin T cell - Step 1

Answer 11

• A specific pathogen antigen activates a T cell to mature into a CTL
• placing an antigen-specific T-cell receptor (TCR) on its surface

Question 12

Cytotoxin T cell - Step 2

Answer 12

An infected host cell processes pathogen proteins and presents them on its surface on MHC-I

Question 13

Cytotoxin T cell - Step 3

Answer 13

If the MHC-I–presented antigen matches the CTL’s TCR, the cells join with help from CD8

Question 14

Cytotoxin T cell - Step 4

Answer 14

• This joining triggers the CTL to secrete perforins/granzymes, lysing the infected host cell
• the released intracellular pathogens are then phagocytosed and killed by neighboring phagocytes