ageing of the immune system

Question 1

basic characteristics

Answer 1

immediate- responds to infection rapidly
non specific- responds in a general manner to any threat
no memory- immune system doesnt develop immunological memory
inflammatory response- immune cells recruited, fever, inhibiting pathogen growth and promotes host cell defence mechanisms

Question 2

innate immune system components

Answer 2

physical barriers- skin, mucous membranes, cilia (small hairs), acidic environments eg stomach acid = 1st layer
humoural response- proteins found in body fluids, such as antimicrobial peptides that help or inhibit the growth of pathogens = 2nd layer
cellulaer components- cells that play an essential role in detecting and eliminating pathogens

Question 3

neutrophils

Answer 3

primarily responsible for engulfing and destroying pathogens, specifically bacteria, through phagocytosis

Question 4

basophils and eisonophils

Answer 4

protective against parasites and are mediators of an allergic response

Question 5

macrophages

Answer 5

very efficient phagocytes, called monocytes in blood and macrophages in tissue, patrol for pathogens and dead cells, can activate T cells via antigen presentation

Question 6

mast cells

Answer 6

are in connective tissue, generally involved in wound healing and an inflammatory response, through mediators such as histamines and cytokines

Question 7

dendritic cells

Answer 7

located in tissue, in direct contact with external environment, primarily act as messengers and are a bridge between innate and adaptive immunity

Question 8

natural killer cells

Answer 8

do not attack pathogen directly, induce apoptosis through the release of cytokine proteins

Question 9

adaptive immune system characteristics

Answer 9

specific response- targeted response, tailored to recognising and eliminating specific antigens (slower response)

memorise- after an encounter, certain immune cells will remember the pathogen for next time

lymphocytes- T and B cells that undergo clonal expansion- quickly expan to make 1000s of more cells

antigen presentation- dendritic cells play a crucial role by capturing antigens from pathogens and presenting them to T cells- to ensure the cells recognise the receptor

adaptive- activation and expansion of antigen specific lymphocytes and prod of antibodies

Question 10

T cells

Answer 10

in the adaptive immune system
come from the thymus, involved in cell mediated immunity, directly attack infected or abormal cells and coordinate an immune response

helper- recognise antigens and release cytokines to activate other immune cells incl b cells, cytotoxic t cells and macrophages

cytotoxic- directly kill abnormal cells

regulatory- regulate the response eg can suppress the activity of other immune cells

Question 11

B cells

Answer 11

come from bone marrow, produce antibodies which bind specific antigens, marking ghem for destruction by other immune cells or neutralise their activity directly

plasma cells- secrete large amounts of antibodies
memory b cells- provide immunological memory to an antigen

Question 12

immune cell proportions

Answer 12

majority of t and b cells are in lymphatic system
lots of neutrophils, basophils and eosinophils are in bone marrow

neutrophil- 50-70%
lymphocyte- 25-50% (t cells-20-40%, b cells 5-15%)
monocyte- 2-10%
eoisinophil- 1-6%
basophil- 0-1%

Question 13

changes with age

Answer 13

disease- any harmful deviation from the normal structure of functional state of an organism

• gradual decline with ahe- ability to mount robust responses is diminished
• immunological memory- decline in production of new immune cells (esp naiive t cells)
• inflammaging- chronic low grade inflammation- increased pro inflammtory cytokines and activation of immune cells
• ## poor immunological surveillance- decreased ability to detect abormal or cancerous cells

Question 14

thymus

Answer 14

thymus is primary lymphoid organ in the chest, responsible for the maturation and selection of T cells, thymic involution is the gradual shrinkage of the thymus that occurs with age

Question 15

thymus involution

Answer 15

gradual shrinlage of the thymus- occurs with age

normal thymic development
- is highly active and plays a central role in t cell development
- immature t cell precursors (thymocytes) migrate from the bone marrow to the thymus where they undergo development and selection

age related changes
- thymic involution begins early in life
- after puberty thymus undergoes progressive atrophy
- by middle age, thymus is larger replaced by adipose and ability to produce t cells is significantly diminished

Question 16

decline in naive t cells

Answer 16

t cell ageing
- naiive t cells are critical for recognising new antigens and mounting an immune response to pathogens
- naiive t cells havent interacted with any cells in the past

Question 17

accumalation of memory cells

Answer 17

t cell ageing
- accumalation of memory t cells which have been previously exposed to antigens
- functionaility may also be impaired

Question 18

impact on t cell receptors

Answer 18

t cell ageing
-alterations in the diversity and specificity of t cell receptors, limits abiloty of t cells to recognise and response to a wide range of antigens (cells cant mount)

Question 19

t cell ageing

Answer 19

collectively increases the susceptibility to infection, may reduce the effectiveness of vaccines and alterations in t cell responses, can lead to tissue damage, inflammation and disease profression

Question 20

altered b cell function

Answer 20

b cell ageing
decline in the production of antibodies
weakened immune response

Question 21

impact on vaccine response

Answer 21

b cell ageing
reduced antibody production and lower vaccine efficacy

Question 22

role in autoiummune diseases

Answer 22

b cell ageing
involved in the development of autoimmune diseases where the immune system mistakenly attacks the body’s own tissue

Question 23

b cell ageing

Answer 23

increases the susceptibility to infection, may reduce the effectiveness of vaccines and icreases the risk of chronic inflammatory autoimmune diseases such as rheumatoid arthritis, systemic lupus and multiple sclerosis

Question 24

changes to innate immune system

Answer 24

decreased activity on natural killer cells
impaired phagocytic function (incl macrophages and neutrophils)
dysregulated cytokine production
delayed wound healing
chronic state of low grade inflammation

Question 25

inflammation

Answer 25

while inflammation is a normal response of the immune system to infection or injury, ageing is associated with a state of dysregulated and prolonged inflammation
- persistant low level inflammatory state persists over time , characterised by sustained activation of the immune system and prod of pro inflammatory cytokines
- chronic inflammation contributes to tissue damage, dysfuntion and progression of disease
- sweked response in acctivity of cells

Question 26

healthy ageing

Answer 26

involves adopting lifestyle habits aimed at maintaining optimal health
diet rich in vit C, D and E , zinc, selenium and antioxidants can slow down ageing of immune system
adequate sleep associated with improved immune regulation
chronic stress can have detrimental effects on immune function
regular physical activity associated with improved immune function