ageing of the immune system Flashcards
basic characteristics
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
innate immune system components
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
neutrophils
primarily responsible for engulfing and destroying pathogens, specifically bacteria, through phagocytosis
basophils and eisonophils
protective against parasites and are mediators of an allergic response
macrophages
very efficient phagocytes, called monocytes in blood and macrophages in tissue, patrol for pathogens and dead cells, can activate T cells via antigen presentation
mast cells
are in connective tissue, generally involved in wound healing and an inflammatory response, through mediators such as histamines and cytokines
dendritic cells
located in tissue, in direct contact with external environment, primarily act as messengers and are a bridge between innate and adaptive immunity
natural killer cells
do not attack pathogen directly, induce apoptosis through the release of cytokine proteins
adaptive immune system characteristics
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
T cells
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
B cells
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
immune cell proportions
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%
changes with age
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
thymus
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
thymus involution
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
decline in naive t cells
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
accumalation of memory cells
t cell ageing
- accumalation of memory t cells which have been previously exposed to antigens
- functionaility may also be impaired
impact on t cell receptors
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)
t cell ageing
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
altered b cell function
b cell ageing
decline in the production of antibodies
weakened immune response
impact on vaccine response
b cell ageing
reduced antibody production and lower vaccine efficacy
role in autoiummune diseases
b cell ageing
involved in the development of autoimmune diseases where the immune system mistakenly attacks the body’s own tissue
b cell ageing
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
changes to innate immune system
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
