5.4 B-lymphocytes and humoral immunity

Question 1

Why is humoral immunity called as such?

Answer 1

it involves antibodies, which are soluble in the blood and tissue fluids (i.e. the ‘humours’ of the body)

Question 2

What do B-cells do upon encountering a complementary antigen?

Answer 2

-the antibodies on the B-cell’s surface will attach to a complementary antigen
-the antigen will enter the B-cell by endocytosis and be presented on its surface (processed)
-helper T-cells bind to these processed antigens and stimulate the B-cell to rapidly clone itself by mitosis, all of which produce the complementary antibody to the antigen.
-this process is called clonal selection

Question 3

What are the two types of B-cell?

Answer 3

-plasma cells. these secrete antibodies at ~2000/s, but only survive for a few days
-memory cells. these can live for decades, and do not produce antigens, instead circulating in blood+tissue fluids. upon encountering the same antigen which triggered their creation, they rapidly divide and develop into plasma cells and more memory cells

Question 4

What is the primary immune response?

Answer 4

the production of antibodies and memory cells upon first encounter with an antigen

Question 5

What is the secondary immune response?

Answer 5

the cloning of memory cells and quicker, greater release of antibodies upon reinfection of the same antigen