Allergies and the Immune System: How Small Changes Trigger Big Reactions

The immune system is the body’s first line of defense, protecting us from infections, pathogens, and harmful invaders. However, sometimes the immune system overreacts or reacts inappropriately to harmless substances, such as allergens like pollen, dust, dander, or venom, which results in an allergic reaction. Shifts and changes in the immune system causes by genetic factors, environmental influences, and certain conditions can predispose someone to a potential allergic response that they may not have experienced previously.

At its core, the immune system is designed to identify and neutralize harmful antigens such as bacteria, viruses, and fungi. It consists of various components, including white blood cells, antibodies, and a complex system of organs and proteins. When the immune system encounters a pathogen, they respond to try and eliminate the threat. The normal immune response is what keeps the body healthy and maintains homeostasis.¹

Allergies occur when the immune system mistakenly identifies a typically harmless substance, like allergens, as a threat. The immune response involves the release of chemicals like histamine, leading to symptoms like itching, swelling sneezing, and more severe reactions like anaphylaxis. Simplistically, allergies are a case of the immune system being “overprotective”.

Environmental factors play an equally significant role in allergy development. The “hygiene hypothesis” suggests that living in overly clean environments can prevent the immune system from being exposed to a wide range of bacteria and viruses early in life. This lack of exposure may shift the immune system towards a more allergic (Th2) response, as it hasn’t learned to differentiate between harmful and harmless invaders.⁵

Pollution, urbanization, and climate change have also been linked to rising allergy rates, as they can affect how the immune system interacts with common allergens. For example, people living in urban areas may be exposed to higher levels of airborne pollutants, which can prime the immune system for allergic reactions. Similarly, climate change is causing longer pollen seasons and higher pollen counts, increasing exposure to allergens like grass and tree pollen.

This imbalance is linked to early childhood environments. According to the hygiene hypothesis, reduced exposure to infections in childhood can lead to an underdeveloped Th1 response and an overreactive Th2 resposne. This imbalance makes children more susceptible to developing allergies as they grow older.^5,9

Allergy immunotherapy is a treatment method that involves gradually exposing individuals to small amounts of an allergen over time to desensitize the immune system. This process reduces the severity of allergic reactions by training the immune system to recognize allergens as harmless. HollisterStier Allergy provides a variety of extracts to conduct allergy immunotherapy treatments in the clinical setting.

Regular exercise, stress management, and avoiding smoking or excessive alcohol consumption can also support a balanced immune response. Conversely, a diet high in processed foods or exposure to chronic stress can exacerbate immune dysfunction and contribute to the development of allergies.

The immune system is a complex network that protects us from harm, but it’s not always perfect. Changes in the immune system, whether due to genetics, environmental factors, or health conditions, can tip the scales toward developing or experiencing allergies. Understanding the intricate relationship between immune shifts and allergies can empower people to manage and potentially prevent allergic reactions through treatments like immunotherapy.