The Ageing Immune System Flashcards
What are the two types of immunity?
Innate and acquired
What is the general consensus in regards to ageing and immunity?
Findings have led to suggestions that there may be an association between the function of the immune system, the ageing process in general, and age-related diseases
What does the immunological theory of ageing state?
Innate and acquired immune functions decline with age
Mortality rates due to infectious diseases can be much greater over the age of 65
Involution of the thymus and reduced tolerance lead to greater occurrence of autoimmune diseases
What are the aspects of the innate immune system at birth?
physical barriers Digestive acids Macrophages Neutrophils Natural killer cells
How is bone marrow effected by age?
Generates normal numbers of immune cells
How are neutrophils effected by ageing?
No decline in numbers but small reductions in
release, chemotaxis & phagocytosis
How are Macrohages effected by ageing?
no decline in numbers but small reductions in phagocytosis and cytokine production
How are Natural killer cells effected by ageing?
increased numbers but no change in killing or cytokine production
How are B cells effected by ageing?
numbers do not decline, but there are age related falls in clone expansion and
antibody production, due to reduced T-cell help
How is the thymus effected by ageing?
Significant atrophy (90% by age 70) mainly due to thymus epithelial cells loss
How are T cells effected by ageing?
Age related fall in naive T-cell production /
maturation and reduced cytokine release
What is the most obvious effect of ageing on the immune system?
Reduced naïve T-cell formation and thymus involution
How does thymus size change over time?
By 50 new T cell production reduced by 20%
By 70 new T cell production has stopped
What is the role of functioning T cells in immunity
Release lymphokines which will attract other immune cells to digest the pathogen. Some become memory cells.
What is the role of functioning B cells in immunity
attaches and digests pathogens then displays antigens on its surface
What is the role of adaptive immunity?
Responses to pathogens such as viruses,
bacteria, fungi, protozoa by antigen-specific B-cells / T-cells
What is the cause of transplant rejection?
Immune responses to non-self skin grafts, organ transplants and blood transfusions
What is Graft vs host disease
Occurs when bone marrow transplant cells raise immune responses to the host whose immune system has been eliminated by chemotherapy or radiotherapy
What is a autoimmune disease?
When immune cells of the body attack self cells unnecessarily
What are the requirements for T cell recognition?
T-cell receptor (TCR)
MHC molecule
Presented antigenic peptide
What several examples of autoimmune disease?
Goodpasture’s syndrome, Rheumatic fever,
Graves’ disease, Myesthenia gravis
Type 1 diabetes
What is Type III hypersensitivity?
Soluble immune complex
deposition in tissues causing adverse effects
What is type IV hypersensitivity?
caused by T helper-cell cytokines:
Will cause:
Type 1 Diabetes, Rheumatoid arthritis, Multiple sclerosis
How many people suffer with autoimmune disease in there life?
1 in 30 individuals in the UK
What is the cause of Hashimotos’ thyroiditis?
Thyroid gland enlargement
(goitre) due to immune cell
infiltration causing thyroid function loss (hypothyroidism)
What is Graves disease?
Over production of thyroid hormone leading to exopthalmos (bulging eyes), heat intolerance and anxiety
What is the cause of type 1 diabetes mellitus?
immune cell infiltration and
selective destruction of insulin-producing cells in the pancreas
How many autoimmune diseases occure after the age of 40?
26
Why are autoimmune diseases more prevalent in women
Female sex hormones have a role in autoimmune diseases susceptibility but the mechanisms are poorly understood
What happens to auto reactive TCRs as we age?
easily removed in early life but much less in old age
What effect does ageing have on T-cells?
Increase the proportion of activated T-cell clones
How are B cells effected when interacting with T cells as we age?
T cell help activating B cells is reduced
What drugs are prescribed for autoimmune diseases?
Prenisolone
Azathiopine
What drugs can induce autoimmune disease?
Procainamide
Hydralazine
what diseases become more prevalent in the elderly?
Influenza
Pneumonia
Septicaemia
