Immunity

Question 1

What is the innate immune system?

Answer 1

The first line of defence in the body

Question 2

What cell types make up the adaptive immune response

Answer 2

B cells (plasma and memory cells)T cells (Th and Tc cells)NK cells (Natural Killer)

Question 3

Where are immune cells found in the body

Answer 3

Lymph nodes/lymphatic vesselsThymusSpleenBone marrow

Question 4

What are the two parts of the adaptive immune system

Answer 4

Humoral immunity Cell-mediated immunity

Question 5

What are the key features of humoral immunity

Answer 5

Acts against antigens; antibody mediatedUtilises B lymphocytesActs by circulating antibodies in serum; defends against extracellular pathogens/bacteria/virus

Question 6

What are the key features of cell-mediated immunity

Answer 6

Acts against viruses/bacteria/fungi/parasites/cancer/transplants etc. Utilises T lymphocytesActs by direct cell contact or secreted soluble products; defends against intracellular bacteria

Question 7

What physiological VASCULAR changes occur during the innate inflammatory response

Answer 7

Dilation of small arterioles (increasing blood flow)Increased vascular permeability (plasma leaks into inflamed area)Mediators (PGs, histamine, PAF, bradykinin, NO) cause vasodilation and permeability.

Question 8

What physiological CELLULAR changes occur during the innate inflammatory response

Answer 8

Chemical mediators producedWhite blood cells move into inflamed tissues to help destroy microorganisms

Question 9

What physiological changes occur during the INDUCTION phase of the adaptive inflammatory response

Answer 9

Lymphocytes primed, ready to recognise specific antigenic moleculesT helper cell regulate development of response (T1 - cell-mediated; T2 - antibody-mediated)

Question 10

What physiological changes occur during the EFFECTOR phase of the adaptive inflammatory response

Answer 10

Antigen-bearing cells destroyed through action of secreted antibodies.

Question 11

What physiological changes occur during the EFFECTOR phase of the adaptive HUMORAL response

Answer 11

Lymphocytes converted to Th2 cells.Th2 cells stimulate B lymphocytes to convert to plasma cells.Plasma cells enter blood, and secrets antibodies for antigen recognition/degradation.

Question 12

What physiological changes occur during the EFFECTOR phase of the adaptive CELL-MEDIATED response

Answer 12

Lymphocytes converted to Th1 cells, which are converted to cytotoxic (Tc) cells. Tc cells activate other immune molecules and kills antigen presenting cells.

Question 13

Give some examples of factors that can induce the inflammatory response

Answer 13

Microorganisms (bacteria/viruses)Radiation (heat, UV, radioactivity)Biochemical damage (metabolic poisons, anoxia)Mechanical trauma (scratch, cut)Non-harmful factors (grass, pollen etc)

Question 14

Give some examples of innate immunity

Answer 14

Cough reflexEnzymes in tears/skin oilMucusSkinStomach acid

Question 15

What are the two components of the innate inflammatory response

Answer 15

Vascular eventsCellular events

Question 16

Give examples of unwanted inflammatory/immune responses

Answer 16

Schistosomiasis. most tissue damage/symptoms are due to immune responseAnthracosis (black lung disease). Caused by immune response to coalSevere acute respiratory syndrome (SARS). Deaths are due to excessive immune response.

Question 17

How do phospholipase A2 (PLA2) mediators work

Answer 17

Enzyme found in most cell types. Stimulation of cells by inflammatory mediators/cell damage activates PLA2.PLA2 metabolises phospholipids in the cell membrane as first step in forming:Prostagladins, leukotrienes, platelet activating factor.

Question 18

Describe the cascades activated by plasma factor 12.

Answer 18

PF12 found in blood plasma. When it leaks into tissues, comes into contact with extracellular proteins (e.g. collagen). This convers PF12 to Factor 12a. Factor 12a activates protease enzymes in signalling pathways. This generates:Bradykinin; ‘complement’ factors (can activate mast cells, or attach to microorganisms to degrade or facilitate degradation)

Question 19

How do ‘reactive’ oxygen molecules act as a chemical mediator in the inflammatory response

Answer 19

Macrophages have enzymes that can synthesis: Superoxide anion (O2-), hydrogen peroxide (H2O2), Nitric oxide (NO) etc.Kills microorganisms by reactions that cause damage to lipid/protein structure. Can damage own cells.

Question 20

Give some examples of pro-inflammatory cytokines

Answer 20

Interleukin 1-alpha and 1-betaTumour necrosis factor-alphaInterferons (esp interferon-gamma)

Question 21

What role do cytokines play in the inflammatory response

Answer 21

Cytokines are peptides synthesised/released by immune cells.Can be pro- or anti- inflammatoryCytokines bind to receptors on target cells, activated intracellular signalling pathways (promoting/inhibiting gene transcription in targen nucleus)

Question 22

What chemical mediators are derived from mast-cells

Answer 22

Various receptors on mast-cell membranes can bind to:IgE antibodies and some complement factorsWhen they bind to the receptor the mast cell releases:Histamine, leukotrienes, PGD2, platelet activating factor (PAF)