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
DEC 27, 2020
Microbiology
A Potential Treatment Approach for Crohn's Disease
DEC 27, 2020
A Potential Treatment Approach for Crohn's Disease
Researchers may have found a way to treat or prevent Crohn's disease, one of the most common forms of inflammatory bowel ...
JAN 05, 2021
Immunology
Immune Imbalances Dictate COVID Symptom Severity
JAN 05, 2021
Immune Imbalances Dictate COVID Symptom Severity
COVID symptoms. “As it is often the case for pathogenic infections, the host immune system is a key player in vira ...
JAN 28, 2021
Neuroscience
Immune Cells Destroy Synapses in Multiple Sclerosis
JAN 28, 2021
Immune Cells Destroy Synapses in Multiple Sclerosis
Researchers from Germany have found that Multiple sclerosis (MS)-associated inflammation in the cerebral cortex destroys ...
FEB 23, 2021
Immunology
Immune Link Explains Why Personality Influences Mortality
FEB 23, 2021
Immune Link Explains Why Personality Influences Mortality
University of Limerick researchers have discovered direct links between the immune system, specific personality traits, ...
MAR 22, 2021
Immunology
Gene Mutation Keeps Tumors "Cold"
MAR 22, 2021
Gene Mutation Keeps Tumors "Cold"
Immunologists have identified a mechanism through which an oncogene mutation shields pancreatic tumors from immune cells ...
APR 06, 2021
Immunology
Lymphoma Patient Cured by "Reeducating" their Immune System
APR 06, 2021
Lymphoma Patient Cured by "Reeducating" their Immune System
Australian researchers have used a breakthrough therapy to cure a patient diagnosed with a rare brain lymphoma, a form o ...
Loading Comments...