5.4 - B lymphocytes and Humoral Immunity

Question 1

Secondary immune response process:

Answer 1

1. production of antibodies is quicker after exposure to the pathogen
2. conc. of antibodies increases quickly
3. memory cells recognise the pathogen’s antigens and quickly divide into plasma cells
4. plasma cells secrete larger nuber of antibodies to quickly destroy the pathgoen before the individual experiences any symptoms

Question 2

Primary immune response process:

Answer 2

1. production of antibodies is slow after first exposure to the pathogen
2. conc. of antibodies increases slowly
3. this is due to few B cells that are specific to the pathogen’s antigens
4. Takes time for the B cells to divide into plasma cells to produce the current antibody - individual therefore experiences symptoms of the disease
5. some B cells divide into memory cells to become immune

Question 3

First exposure and second exposure antibody concentration trend on graph

Answer 3

Question 4

What is the secondary immune response? (when does it occur and what is the response like)

Answer 4

• body is exposed to the same pathogen before
• response is faster - pathogens are destroyed before any symptoms appear

Question 5

What is the primary immune response? (when does it take place and what is the response and what does the individual experience):

Answer 5

• when the body is exposed to a pathogen for the first time
• response is slow
• infected individual experiences symptoms of the disease

Question 6

What is clonal expansion?

Answer 6

division of specific B cells to produce genetically identical clones

Question 7

What is clonal selection?

Answer 7

B cell with the correct antibody is selected for cloning (being activated by a Th cell)

Question 8

Stages of the humoral response

Answer 8

1. A B cell with a complementary antibody binds to the antigens on a pathogen.
2. The B cell engulfs the pathogen and presents its antigens on the cell-surface membrane to become an antigen-presenting cell.
3. Clonal selection - Activated T helper cells bind to the B cell, causing activation of this B cell.
4. Clonal expansion - The activated B cell divides by mitosis to form plasma and memory cell clones.
5. The cloned plasma cells produce and secrete the specific antibody which is complementary to the antigen on the pathogen’s surface. These antibodies attach to antigens on pathogens and destroy them.
6. The memory cells circulate the blood and tissue fluid, ready to divide if the body is re-infected by the same pathogen.

Question 9

What do Th cells do in humoral response (what does it bind to and activate)?

Answer 9

binds to an APC to activate the division of B cells

Question 10

What do memory cells do in humoral response (what type of cell, how long is the immunity and what against, lifespan and what happens if it’s reinfected by a pathogen):

Answer 10

• type of B cell
• long term immunity against specific pathogens
• longer lifespan than plasma cells
• rapidly divide into plasma cells - only if re-infected by the same pathogen

Question 11

What do plasma cells do in humoral response (what are they a type of, what do they secrete, lifespan):

Answer 11

• type of B cell
• secrete antibodies against a specific antigen
• lifespan of a few days

Question 12

What do B cells do in humoral response: (what do they have on their surface, what do they become and how, what happens once they activate):

Answer 12

• have antibodies on their cell-surface membrane - bind to complementary antigens
  1. engulf the antigens and become APCs by displaying it on their cell-surface
  2. once activated, they divide into plasma cells and memory cells

Question 13

What cells are involved in humoral response (4):

Answer 13

B cells
Plasma cells
Memory cells
Th Cells

Question 14

Humoral response (what does it use, what does it produce):

Answer 14

• involves the use of B lymphocytes/B cells
• produce and are covered in antibodies (proteins)

Answer 15

the production of specific antibodies to destroy pathogens