What Happens When Your Immune System Forgets
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…
