Humoral immunity

Question 1

What does the humoral immune system respond to

Answer 1

Pathogens found in body fluids (mainly the blood stream, but also in the tissue fluid that surrounds the cell)

Question 2

Where do B-cells mature in

Answer 2

Bone marrow

Question 3

What are the 2 types of B-cells

Answer 3

• Plasma cells
• Memory cells

Question 4

Describe the function of plasma cells

Answer 4

Produce antibodies

Question 5

Describe the function of memory cells

Answer 5

Divide rapidly and differentiate into plasma cells if they encounter the same antigen again

Question 6

When does humoral immunity occur?

Answer 6

Humoral immunity is a response to infection in body fluids such as blood plasma (this used to be called ‘humour’, hence the name humoral immunity). This can include bacteria, toxins, antigens or abnormal cells.

Question 7

Describe the response of B-lymphocytes to a foreign antigen (humoral response)

Answer 7

• Each type of B cell has a different type of antibody on its surface. These will bind to any complementary antigens in the blood stream or tissue fluid.
• The antigen enters the cell by endocytosis.
• The antigen is presented on the cell surface membrane. We say that it has been ‘processed’.
• T Helper cells bind to the processed antigen, stimulating the B cell to divide by mitosis – this is called clonal selection.
• The B cell clones develop into one of two cells: Plasma cells secrete antibodies to destroy the pathogen, however they only live a few days. This is the primary response. Memory cells live for decades. When the same pathogen is encountered, they divide rapidly into more plasma cells and memory cells. This is the secondary response

Question 8

Why is it important that the B cells produce many clones of itself

Answer 8

So they have the same receptors and can therefore bind to the same antigens