MAR 16, 2021 8:00 AM PDT

What Happens When Your Immune System Forgets

WRITTEN BY: Tara Fernandez

One of the most remarkable features of the immune system is its ability to “remember” past encounters with pathogens like viruses, bacteria, and parasites. This phenomenon, known as immunological memory, is controlled by two main immune cell types: memory T and B cells.

After bouncing back from an infection, the immune memory adds the pathogen to its database, priming it to react rapidly if the same infectious agent invades again. Antigen-specific T cells hang around for years after an infection, waiting in the wings to explode in numbers upon reexposure. Additionally, B cells, factories that churn out pathogen-killing antibodies, also help shield against subsequent infections. Upon sensing a familiar pathogen, B cells will metamorphose into plasma cells, secreting antibodies that bind to the invader with exquisite specificity.

Immune memory is the very reason vaccines work, a process that has been exploited routinely in vaccination programs across a spectrum of disease-causing agents for over 200 years. Administering a small, innocuous fragment of the pathogen generates immune memory without the patient having to experience a full-blown infection.

The problem is that immune memory can taper off over time. In general, it’s believed that this fade-out happens because not all long-term memory T cells live long enough to confer life-long protection. However, the precise cellular mechanisms underlying immune memory fade still elude scientists, mostly because these processes are difficult to explore experimentally.

What we do know is that if we are exposed to a pathogen in childhood or adolescence, we generate robust and long-lasting immunity against it, especially if we are exposed to it several times. However, this process is not quite as effective if we encounter the pathogen as an adult.

Immune memory is currently in the spotlight in the context of COVID infections, particularly as so little is known about how natural infections and vaccines impart long-lived immunity. From the data we have, it’s unlikely that the answer will be a straightforward one. For instance, after COVID infection, antibodies decay more quickly in men than women. In terms of vaccinations, many of the treatments given emergency-use-authorization use delivery methods such as mRNA nanoparticles and viral vectors, relatively new modalities. 

Though initial studies demonstrate that these are effective in providing individuals with rapid protection against the coronavirus, how well they activate memory T and B cells and how long this protection lasts remains to be seen.

 


 

About the Author
  • Tara Fernandez has a PhD in Cell Biology and has spent over a decade uncovering the molecular basis of diseases ranging from skin cancer to obesity and diabetes. She currently works on developing and marketing disruptive new technologies in the biotechnology industry. Her areas of interest include innovation in molecular diagnostics, cell therapies, and immunology. She actively participates in various science communication and public engagement initiatives to promote STEM in the community.
You May Also Like
AUG 24, 2021
Health & Medicine
Myocarditis and COVID-19 Vaccination
AUG 24, 2021
Myocarditis and COVID-19 Vaccination
Myocarditis has been linked to sudden cardiac death in young, healthy athletes and smallpox, influenza, hepatitis B, and ...
SEP 07, 2021
Health & Medicine
Vaccines- a Long History of Cost-Benefit Analysis
SEP 07, 2021
Vaccines- a Long History of Cost-Benefit Analysis
Vaccination and new treatments for diseases have remained topics of skepticism since their inception. When it came to an ...
SEP 14, 2021
Immunology
The Spleen Creates Long-Lasting Protection Against the Flu Virus
SEP 14, 2021
The Spleen Creates Long-Lasting Protection Against the Flu Virus
You share an elevator with an individual who is coughing and sneezing, only to find yourself feeling unwell a few days l ...
SEP 23, 2021
Cardiology
Curbing Adverse Cardiovascular Outcomes Through Influenza Vaccination
SEP 23, 2021
Curbing Adverse Cardiovascular Outcomes Through Influenza Vaccination
Influenza is a severe infectious disease. According to the Centers for Disease Control and Prevention the H1N1 strain of ...
OCT 18, 2021
Genetics & Genomics
A Decade After Gene Therapy, SCID Patients Are Doing Well
OCT 18, 2021
A Decade After Gene Therapy, SCID Patients Are Doing Well
For decades, scientists have been trying to find ways to cure disorders that can be traced back to an error in one gene. ...
NOV 16, 2021
Immunology
How a BBQ Lighter Inspired a New Vaccine Technology
NOV 16, 2021
How a BBQ Lighter Inspired a New Vaccine Technology
It’s the size of a pen, weighs as much as two AA batteries, and works without a power source. A new microneedle de ...
Loading Comments...