Allergies and Immune System

Your immune system’s main job is to recognize dangerous microbes and destroy them using a coordinated network of cells and chemical signals. When it detects a threat, it produces antibodies and inflammatory molecules that help clear the invader and then return to balance once the job is done.

In allergies, the system mistakes harmless substances—like pollen, pet dander, dust mites or certain foods—for real danger. Specialized B cells switch to making immunoglobulin E (IgE) antibodies against these allergens, which bind to mast cells and basophils, priming them for rapid reaction.

The next time you encounter the allergen, IgE on mast cells triggers a burst of histamine and other mediators, causing sneezing, itching, wheezing, hives or even anaphylaxis in severe cases. This is called a type I hypersensitivity reaction and is a hallmark of many common allergic diseases.

Allergic inflammation is dominated by type‑2 immune responses involving Th2 helper T cells, innate lymphoid cells type 2 (ILC2), eosinophils, mast cells and IgE‑producing B cells. Th2 cells release cytokines like IL‑4, IL‑5 and IL‑13, which drive IgE production, eosinophil activation and mucus secretion in airways and skin.

Regulatory T cells (Tregs) and other regulatory mechanisms normally keep these reactions in check and promote tolerance to everyday exposures. When Treg function is impaired, type‑2 inflammation can spiral, increasing the risk of severe asthma or food allergy.

New research highlights additional regulatory players, including specific B cells producing IgA and IgG that can block IgE’s actions on mast cells and help reduce allergic responses, especially in the gut. Recently identified intestinal dendritic cells and immune cell subsets are emerging as crucial for preventing food allergies by actively promoting tolerance to dietary proteins.

Allergies and autoimmune diseases are both caused by inappropriate immune responses, but they target different things: allergies react to external, harmless substances, while autoimmunity attacks the body’s own tissues. Both involve misdirected T and B cells, chronic inflammation and overlapping genetic risk factors.

Large genetic studies in 2024–2025 show complex links between allergic diseases (like allergic rhinitis, asthma and atopic dermatitis), autoimmune conditions (such as psoriasis and type 1 diabetes) and chronic rhinosinusitis. Shared pathways—especially involving type‑2 cytokines and the IL‑33 signaling axis—help explain why asthma and sinus disease often occur together.

These connections support the “one airway, one disease” concept: inflammation in the nose, sinuses and lungs is often part of a single, system‑wide immune process rather than separate problems.

In 2025, experts warn that worsening air quality and climate change are intensifying pollen seasons, changing where plants grow and potentially making allergens more potent. Pollution can damage airway barriers and prime the immune system, making it easier for allergens to trigger type‑2 inflammation.

Viral infections may also disrupt immune balance, sometimes overstimulating the system and contributing to the development or worsening of allergies and asthma. At the same time, reduced exposure to diverse microbes—through urban living or overuse of certain antiseptics—may limit the training of regulatory pathways that normally build tolerance.

Together, genetics, environment, infections and lifestyle shape whether your immune system tolerates everyday exposures or tips into allergy. This is why allergies can emerge or change over time, even in adults.

Traditional treatments like antihistamines and nasal steroids mainly block symptoms such as itching and congestion, but they do not fix the underlying immune misfire. Newer biologic drugs target specific cytokines (IL‑4, IL‑5, IL‑13) or IgE itself, directly dialing down type‑2 inflammation in asthma, eczema and chronic sinus disease.

Researchers are also refining allergen immunotherapy (allergy shots or tablets), which works by gradually retraining the immune system to tolerate allergens and boosting protective IgG and regulatory responses. Experimental approaches aim at pathways like IL‑33 or enhancing regulatory cells in the gut and airways to prevent allergies before they start.

For individuals, combining medical treatment with practical steps—managing exposure, supporting overall health and following care plans—offers the best chance to keep the immune system balanced and allergies under control in today’s changing environment.