How do we sometimes get allergies much later in life, even if we have been exposed to the allergens for a few years?

Question

All,

I moved to a new country about a decade ago and didn’t have any issues. However, 3 years ago I started getting pollen allergies and they are only getting worse each year. My doctor said that it happens that we randomly get allergies and they can last even the decades.

How does this happen?

In: Biology

Answer 1

Million dollar question with no definitive answer.

Tolerance in immunology is an active process, not just the absence of aggression. Occasionally, failures in tolerance cause people to develop aggressive immune responses to “innocent” or self-antigens. The mechanisms involved differ from one person, one antigen to another, and generally are not entirely understood.

Maybe a dendritic cell got up on the wrong side of the bed one day, decided that pollen allergen needed to be nuked from orbit, and got that message through to a few T cells. Boom, allergy.