On Thursday, BBC Radio 4’s ‘In Our Time’ explored the complex role of T-cells and the biological mechanisms driving immune system ageing.
The discussion detailed how the thymus (a specialized organ of the immune system and endocrine system, located in the upper chest directly behind the breastbone and in front of the heart) that produces and trains T-cells (thymus-lymphocytes, which are white blood cells that help your body fight infections and diseases) shrinks post-puberty, leading to T-cell exhaustion, chronic “inflammageing,” and reduced vaccine efficacy in older adults.
You can listen to the discussion here. It is also repeated tonight (Sunday 1st) at 11pm.
The programme blurb says: “Every day, billions of specialised cells work to protect your body from harm. From the common cold and infections to cuts and scrapes or cancerous cells, our bodies deal with a range of potential threats and risks as we move through the world. The immune system is a complex and carefully orchestrated network connecting organs, tissues, and billions of specialised cells. Those cells have a variety of different roles as they respond to pathogens or harm, including engulfing microbes, identifying damage, or producing antibodies. Misha Glenny and his guests examine the different types of cells involved in an immune response, how they know what to respond to, and what happens when those cells aren’t working as they should. This In Our Time episode discusses why our immune cells are vital to life – both for us as individuals, and as a species. The discussion explores the interconnected nature of the immune system, and what we know actually affects the way our immune cells function.”
Because it was an information dense programme, there is no way that I could summarise what was said. So, for those who are interested, but don’t have an hour to listen, and for those not in the UK (who I don’t think will be able to listen), I asked Gemini (Google’s AI) to summarise (and its summary compared favourably with my recall of the programme):

“The BBC Radio 4 In Our Time panel highlighted several critical mechanisms regarding how our T-cells and broader immune systems change as we age:
1. The Shrinking of the Thymus (Thymic Involution)
• The Problem: The thymus is the specialised organ where T-cells mature and learn to identify pathogens.
• The Ageing Factor: The thymus begins to shrink and fatty tissue replaces its functional areas remarkably early in life, starting right after puberty.
• The Impact: By older age, the output of brand-new, untrained T-cells (naive T-cells) drops significantly. This leaves the body with a fixed, dwindling library of existing cells to fight off entirely new infections.
2. T-Cell Senescence and Exhaustion

• The Problem: T-cells have a limited lifespan and replicative capacity.
• The Ageing Factor: Decades of fighting off chronic, low-level viral infections (such as Cytomegalovirus, or CMV) force a massive portion of the T-cell pool to dedicate itself to these specific targets.
• The Impact: Over time, these constantly active T-cells become “exhausted” or senescent. They remain in the body but lose their ability to divide effectively, crowding out space for cells that could fight new threats like seasonal flus or novel viruses.
3. “Inflammageing”
• The Problem: Ageing shifts the immune system’s default state from responsive to chronically active.
• The Ageing Factor: The panel discussed “inflammageing”—a state of persistent, low-grade, sterile inflammation that develops as we get older.
• The Impact: This constant background noise confuses immune signalling. T-cells become less precise, occasionally leading to slower healing times, reduced vaccine efficacy, and an increased risk of autoimmune reactions where the body mistakenly attacks its own tissues.
4. Reduced Vaccine Response
• The Problem: Vaccines rely on T-cells and B-cells memory creation.
• The Ageing Factor: Because there are fewer naive T-cells available to learn from a vaccine, the immune system Struggles to build a strong memory profile against the injected antigen.
• The Impact: This explains why certain vaccines require higher doses or specific boosters for older demographics to achieve the same level of protection as younger individuals.“

Now that, I think, is a good use of AI. I thought it was a fascinating programme and I learnt a lot that I wanted to share but couldn’t otherwise have done (and if I ever use AI here to produce lumps of text that I post verbatim, without any significant editing, I will always say).
The usual “Lifestyle Strategies” are recommended to preserve t-cell function:
• Eat a balanced diet: Focus on fresh produce, lean proteins, and whole grains to provide essential vitamins and minerals like zinc, folic acid, and vitamins B6 and B12 that support immune cell replication and maturation.
• Exercise regularly: Engage in at least 150 minutes of moderate physical activity each week to help promote healthy immune system functioning.
• Get enough sleep: Aim for 7 to 8 hours of quality sleep every night to allow your body and immune cells to recover.
• Manage stress: Practice relaxation techniques like deep breathing, meditation, or yoga, because high stress can weaken overall immune responses.
• Avoid smoking and limit alcohol: Refrain from smoking or vaping, and keep alcohol consumption to a minimum to prevent immune suppression.
• Practice hygiene and protection: Wash your hands frequently with soap and water, and consider wearing a mask in crowded or poorly ventilated indoor spaces to avoid harmful germs.”