Lecture 10 – Introduction to Immune system

Question 1

Immunology

Answer 1

Study of organs that help prevent against disease.

Question 2

Innate immune system (5)

Answer 2

Epithelial barriers to the environment - skin, GI tract, respiratory tract.
Secretions at muscosal surfaces - flushing action and antimicrobial properties.
Circulating proteins in the blood - e.g. complement proteins.
Cytokines - e.g. interferons, locally produced by infected cells.
Cells that are residents in tissues (e.g. mast cells) or circulating in the body e.g. neutrophils).

Immediate and early protection.

Question 3

How do immune cells know when to get to work? (4)

Answer 3

Detects ‘danger’ through series of PAMPs (Pathogen associated molecular patterns) and DAMPs (Danger associated molecular patterns).
PAMPs - molecular motifs conserved within a class of microbes. e.g. glycans/peptidoglycan.
DAMPs - released by stress cells undergoing necrosis. e.g. heat shock proteins/cytokines.
PAMPs and DAMPs are recognised by Pattern Recognition Receptors (PPRs) on immune cells.

Question 4

Phagocytosis (2)

Answer 4

Process where cells internalise solid matter, including microbial pathogens.
Vital part of innate immune response to pathogens, and plays an essential role in initiating adaptive immune response.

Question 5

Inflammation (5)

Answer 5

Process where immune cells are distributed throughout the body, can be recruited and concentrated to a site of infection/damage.
Following PAMP/DAMP recognitions, PRR trigger proinflammatory and antimicrobial response, inducing release of broad range of cytokines.

Main events:
o Increased blood supply to the affected area.
o Increased permeability of the vasculature.
o Migration of WBCs out of the blood capillaries into the affected tissue.

Question 6

Adaptive immune system (4)

Answer 6

Potent.
Responsive to any potential foreign entity.
Highly specific.
Memory.

Question 7

Adaptive immune system - Main components (4)

Answer 7

1) Dendritic cells – capture, process and present antigens.
2) T lymphocytes – control the immune response by providing “help” to B cells and macrophages (helper T cells); direct killing of infected or tumour cells (cytotoxic T cells).
3) Cytokines – soluble proteins secreted mainly by T cells that control activities of other cells.
4) B lymphocytes – produce and secrete antibodies, proteins that specifically bind target molecules (antigens) on microbes or cells.

Question 8

Lymphoid system (3)

Answer 8

Immunological cells orgnaised intotissues/organs for best efficiency - lymphoid system.
Primary lymphoid organs - Sites of maturation of WBCs, here the differnetiates from stem cells and form mature cells.
Secondary lymphoid organs - Site of interaction for WBC/antigens, spread of immune response.

Question 9

Lymphatic system (1)

Answer 9

Network of lymphatic vessels that carry lymph fluid from tissues back into the blood stream.

Question 10

Lymph nodes (3)

Answer 10

Regular intervals along lymph vessels you have lymph nodes.
Arrive at node by an afferent lymphatic vessel, filters through layers of APC, T/B cells and exits via efferent lymphatic vessel.
Dense conc of immune cells provides ideal environment for initiating immune response and comm between immune cells.

Question 11

Adaptive immunity - recognition of the foreign antigen (2,3)

Answer 11

Immunoglobins (Igs) - Glycoproteins produced by B plasma cells (HUMORAL IMMUNITY). Recognise and bind to SPECIFIC antigens on pathogens and prevent disease.
- Different classes, which diff in structure/function/distribution.

T-cell antigen receptors (TCRs)

• Produced and found on surfaces of T-cells.
• Recognise processed fragements of antigens which are ‘presented’ by host cells.
• TCR + Antigen peptide leads to activation of T lymphocyte via biochemical effects (signal transduction), leads to cell proliferation.

Question 12

B cells (1)

Answer 12

Lymphocytes which are activated when they beocome plasma cells and then produce antibodies - HUMORAL immunity.

Question 13

Antibodies (3)

Answer 13

Glycoproteins.
Made by B plasma cells.
Bind specifically to ‘non-self’ antigens.

Question 14

T cells - cell mediated (cellular) immunity (3)

Answer 14

Control the immune response and combat microbes that are inside cells (intracellular).
Diff T-cells with diff functions, distinguised by CD (Cluster of Differentiation) markers.
Two major group CD4 (helper T cells) and CD8 (Cytoxic T cells).

Question 15

Immunological techniques in diagnostics and research: (2)

Answer 15

Two key features of antibodies – antigen specificity and high affinity binding are extremely valuable in laboratory assays.
They allow rapid and highly sensitive identification of specific molecules.