Immunology - 17

Question 1

Which are the major opsonins generated by complement in what are their functions?

Answer 1

c3b and c4b. There are receptors on neutrophils and macrophages that bind these proteins. They see a pathogen coated in c3b and/or c4b and recognize the flag by receptor binding to eat the bad guy

Question 2

Which are the anaphylatoxins generated by complement?

Answer 2

• c5a (most potent)
• c3a
• c4a

Question 3

How does the immune system detect pathogens that hide inside human cells?

Answer 3

T cells (antibodies are only helpful for extracellular pathogens). Antigenic proteins are broken down in a cell into peptides which are loaded onto MHC molecules and presented to the T cell

Question 4

What is the primary function of the MHC?

Answer 4

Present antigens to T cells (to let the T cells know what is going on inside the cell)

Question 5

What is promiscuous binding?

Answer 5

Thousands of different antigenic peptides must be displayed so each MHC protein must be able to bind and present many different peptides

Question 6

Do all persons have the same MHC class I and II molecules?

Answer 6

No, they are genetically determined by DNA sequence so they vary from person to person

Question 7

In humans, the set of genes that encode MHC molecules is also called?

Answer 7

HLA (human leukocyte antigens)

Question 8

Where do we find MHC class I molecules?

Answer 8

CD8, all nucleated cells (not red blood cells)

Question 9

Where do we find MHC class II molecules?

Answer 9

CD4, on antigen presenting cells (dendritic cells, B cells, and macrophages)

Question 10

What is the main function of MHC class I molecules?

Answer 10

To kill pathogen infected host cells