Immunology refresher

Question 1

Describe the anatomy of lymph nodes

Answer 1

Lymphoid follicles in cortex
Sinuses in medulla

Question 2

what is the role of lymph nodes?

Answer 2

Filter lymph
Immune surveillance
Activation of immune response
Antigen presentation
Production of antibodies
Removal of cellular debris
Transport of immune cells

Question 3

Describe the function of the spleen

Answer 3

Filters and stored blood
Stores WBCs and platelets
Antigen presentation
Haematopoiesis

Question 4

What is the role of tonsils in immunology?

Answer 4

first-line defence against ingested or inhaled pathogens

Question 5

Describe the anatomy of tonsils that aids its immunological role

Answer 5

Crypts increases SA for more interaction between immune cells and pathogens

Question 6

Describe the role of the thymus

Answer 6

T-cell maturation
Education and differentiation
Immunological memory

Question 7

Describe the immunological role of bone marrow

Answer 7

Site of blood cell production including lymphocytes

Question 8

Describe the immunological role of Peyer’s patches

Answer 8

GALT
Immune response in the GIT
Lymphoid nodules in submucosa of the SI

Question 9

What are the components of the innate immune response?

Answer 9

phagocytes
Natural killer (NK) cells
Complement system
Inflammatory response
Cytokines

Question 10

Describe the role of phagocytes in the innate immune response

Answer 10

Neutrophils: Engulf and digest pathogens.
Macrophages: Engulf pathogens, present antigens, and activate other immune cells.
Dendritic Cells: Capture and present antigens to activate adaptive immune responses.

Question 11

What is the role of natural killer (NK) cells in the innate immune response

Answer 11

detect and destroy virus-infected cells

Question 12

Describe the role of the complement system in the innate immune response

Answer 12

Complement proteins enhance the ability of antibodies and phagocytic cells to clear pathogens.
Promote inflammation.

Question 13

Describe the inflammatory response in innate immune response

Answer 13

Release of histamines and other chemicals to increase blood flow and attract immune cells.
Promotes phagocytosis and tissue repair

Question 14

Describe the role of cytokines in the innate immune response

Answer 14

signalling molecules that regulate immune responses

Question 15

What are the components of the adaptive immune response?

Answer 15

T lymphocytes
B lymphocytes
Antibodies (immunoglobulins)
Major histocompatability complex (MHC)
Regulatory T cells
Immunological memory
Cytokines

Question 16

Describe the role of T cells in adaptive immunity

Answer 16

Helper T Cells (CD4+): Coordinate immune responses, activate B cells and cytotoxic T cells.
Cytotoxic T Cells (CD8+): Destroy infected or abnormal cells.

Question 17

Describe the role of B cells in adaptive immunity

Answer 17

Plasma Cells: Produce antibodies that bind to and neutralize pathogens.
Memory B Cells: “Remember” pathogens for faster response upon re-exposure.

Question 18

Describe the role of antibodies/immunoglobulins in adaptive immunity

Answer 18

Bind to pathogens, facilitating their destruction or neutralization.
Opsonization: Enhance phagocytosis by marking pathogens for engulfment.

Question 19

Describe the role of major histocompatability complexes (MHCs) in adaptive immunity

Answer 19

MHC1: Presents intra-cellular antigens to cytotoxic T cells.
MHC2: Presents extra-cellular antigens to helper T cells.

Question 20

Describe the role of regulatory T cells in adaptive immunity

Answer 20

Suppress immune responses to prevent excessive reactions or autoimmune responses.

Question 21

Describe immunological memory

Answer 21

Enhanced response upon re-exposure to a previously encountered pathogen.

Question 22

Describe the role of cytokines in adaptive immunity

Answer 22

Mediate communication between immune cells.
Regulate inflammation, immune cell activation, and differentiation.

Question 23

What are the different complement pathways

Answer 23

Antibody-dependent pathway: links innate and adaptive immunity
Alternative and lectin pathways (antibody-independent): activated directly by interaction with pathogen surface

Question 24

Explain the complement system pathway

Answer 24

Cascade activation of complement proteins => activation of C3 convertase (produced by liver)
C3 convertase => breaks into C3a and C3b
C3a => acts as a chemoattractant and anaphylotoxin (vasoldilation, activate smooth muscle cells, immune cells and increased fluids in tissue)
C3b => binds to microbial surfaces, tagging it for phagocytes with express complement receptors
Membrane attack complex (MAC) is end point => form pores in cell membranes => kills cell

Question 25

What are the key functions of cytokines?

Answer 25

Cell activation and differentiation Inflammation Immune cell recruitment

Question 26

What cells are APCs?

Answer 26

Dendritic Cells: capture, process and present antigens to activate T cells Macrophages: engulf pathogens and present antigens B cells: present antigens to T helper cells during activation of the adaptive immune response

Question 27

Describe the role of major histocompatability complexes in antigen presentation

Answer 27

MHC molecules = cell surface molecules that bind to antigens and transport them to cell surface T cells recognise antigen-MHC complex => activates T cells

Question 28

Describe the process of T cell maturation

Answer 28

Question 29

Describe the process of B cell maturation

Answer 29

Question 30

How do naive T and b cells enter lymph nodes

Answer 30

Circulate in bloodstream Enter lymph nodes via high endothelial venules Initial interaction with endothelial cells through selectins Chemokines induce expression of integrins on lymphocytes promoting adhesion to endothelial cells

Question 31

What is diapedesis?

Answer 31

Naive lymphocytes squeeze through endothelial cells and basement membrane to enter lymph node

Question 32

What is the role of chemokines in the lymph nodes and naive lymphocytes?

Answer 32

guide the migration of naive lymphocytes towards specific areas within the lymph node

Question 33

Describe the activation of naive T cells in the lymph node

Answer 33

Naive T cells interact with dendritic cells that present antigens

Question 34

Describe the activation of naive B cells in the lymph node

Answer 34

naive B cells interact with follicular dendritic cells and encounter antigens