IMI5: integration of innate and adaptive branches of the immune system

Question 1

what are the 3 main steps of the innate immune system?

Answer 1

sensing
inflammation
destruction

Question 2

what are the 3 steps of the complement system?

Answer 2

opsonisation
signalling for help
lysis

Question 3

what type of cell its responsible for the cell-mediated immunity?

Answer 3

T cells

Question 4

what type of molecules are responsible for the humoral immunity?

Answer 4

ab

Question 5

what are the 2 main types of T cells? what are their roles?

Answer 5

cytotoxic T cells–> protect our bodies against pathogens like viruses, bacteria and parasites hat proliferate inside the cell and localise in the cytoplasm or nucleus
helper T cells –> stimulate B cells to secrete ab, stimulate cytotoxic T cells to kill infected target cells and stimulate macrophages to destroy ingested microbes

Question 6

what is the main role of DCs?

Answer 6

act as messengers between the innate and the adaptive arm of the immune system

Question 7

how does the DC act as a messenger?

Answer 7

• when immature DCs detect a pathogen, it phagocytoses it and degrades its proteins into small peptides ==> antigen processing
• primary signal: DCs send to T cells
• secondary signal: so-receptors on DCs interact with ligands on helper T cells
• tertiary signal: DCs secrete a diverse panel of cytokines that allows helper T ells to differentiate to a specific subtype fro the most appropriate response to the specific pathogens

Question 8

what are the 2 signals needed to activate helper T cells?

Answer 8

• recognition of an antigen loaded into the MHC class II molecule by the TCR
• co-stimulatory signal provided by CD80/86 binding to CD28

Question 9

how are cytotoxic T cells activated?

Answer 9

via MHC class I by DCs in a similar fashion BUT cytotoxic T cells need signals from T helper cells too

Question 10

what does the type of cytokine released by DCs do?

Answer 10

determine the type of T helper cell polarisation

Question 11

what are the 3 major functions of DCs?

Answer 11

• serve as sentinel cells and activate innate defences when needed
• process and present antigens ==> initiate adaptive immune responses
• regulate adaptive immunity by determining whether a particular pathogen will trigger a particular T helper response

Question 12

what does the humoral immunity do?

Answer 12

triggers specific B cells to proliferate and secrete huge amounts of their specific ab

Question 13

what is the effect of T helper cells on B cells?

Answer 13

triggers specific B cells to proliferate and differentiate upon binding of the TCR to the antigen-MHC class II complex presented by B cells