The ageing immune system

Question 1

Immunosenescence

Answer 1

Dysregulated immune function = increased susceptibility of elderly to infection and disease

Question 2

Inflammaging

Answer 2

Chronic, low-grade inflammation that develops with advancing age - accelerates biological ageing and worsens age-related conditions

Question 3

innate system

Answer 3

• Skin - decreased epidermal layer and keratinocytes. More water is lost and the skin is less elastic (wrinkles)
• Cilia
• Hair
• Mucosal surfaces
• Flushing action - urine and tears
• Peristalsis

Question 4

Microbial dysbiosis

Answer 4

Immune dysregulation
Oxidative stress
Chronic inflammation

Question 5

Neutrophils and ageing

Answer 5

• Rapid turnover - 1-2 days
• Recruited by chemotaxis
• Kill extracellular organisms - degranulation, phagocytosis and NETosis (NETosis is where myeloperoxidase is released within DNA and break down bacteria)]
• Ageing causes reduced chemotaxis and phagocytosis, apoptosis, and NET formation

Question 6

Macrophages and ageing

Answer 6

T- issue resident cells from monocytes

• Phagocytose pathogens
• M1 are antimicrobial and M2 are used in tissue repair
• Decreased chemotaxis and phagocytosis and apoptosis in ageing

Question 7

Dendritic cells function

Answer 7

• Tissue resident cells
• Antigen presenters
• Migrate to lymph where they encounter T cells 0 talk between innate and adaptive systems

Question 8

NK function and ageing

Answer 8

• Lymphoid lineage - kills virally infected host cells
• Scrutinises cells for loss of MHCI molecules
• Removes cancerous cells and activates macrophages
• As we age, number increases but function decreases

Question 9

CD8 functions

Answer 9

• Activation in LN via APC on MHC i
• Enter periphery and find infected cells
• Recognise infected cells via antigen presented on MHC i
• Kills cells via death receptor pathway (Fas on CD8 binds to Fas on infected cell, cause apoptosis) or release of perforin and granzymes

Question 10

T cells and ageing

Answer 10

• Fills with fat as we age
• Reduced naïve T cells made in periphery
• Increased pro-inflammatory cytokines
• Decreased T cell function - inability to help other processes e.g. B cells
• Incomplete activated T cells travel to tissue = decreased molecular expansion