The mere scent of seafood can trigger violent illness in individuals with allergies to it, leading them to naturally avoid it. Similarly, people who experience food poisoning after consuming a specific meal tend to exhibit avoidance behavior towards that particular food in the future.
While scientists have long known about the immune system’s role in our responses to allergens and pathogens, it remained uncertain whether it played a part in influencing these types of avoidance behaviors related to allergic triggers.
A recent study led by Yale researchers, published in the journal Nature, now reveals that the immune system indeed plays a crucial role in shaping our behaviors.
Ruslan Medzhitov, Sterling Professor of Immunobiology at Yale School of Medicine and the senior author of the study, explains, “We find immune recognition controls behavior, specifically defensive behaviors against toxins that are communicated first through antibodies and then to our brains.”
The research demonstrates that without the immune system’s communication, the brain fails to signal potential dangers in the environment and, consequently, does not initiate avoidance responses.
To explore this further, the team, led by Esther Florsheim and Nathaniel Bachtel, studied mice that had been sensitized to develop allergic reactions to ova, a protein found in chicken eggs. As expected, these mice instinctively avoided water containing ova, while control mice showed a preference for ova-laced water sources. Remarkably, the aversion to ova-laced water persisted for months in the sensitized mice.
The researchers then sought to manipulate immune system variables to alter the behavior of the sensitized mice. They found that blocking Immunoglobulin E (IgE) antibodies, produced by the immune system, caused mice allergic to ova to lose their aversion to the protein in their water.
IgE antibodies play a crucial role in triggering the release of mast cells, a type of white blood cell that, along with other immune system proteins, communicates with areas of the brain responsible for aversion behavior. When IgE is blocked, the transmission of information is interrupted, and the mice no longer avoid the allergen.
Medzhitov believes these findings illustrate how the immune system evolved to help animals avoid dangerous ecological niches. Understanding how the immune system memorizes potential dangers may eventually aid in mitigating excessive reactions to various allergens and pathogens. Such insights hold promise for developing strategies to suppress allergies and other immune-related responses.
Source: Yale University