Allergies and the importance of 5-DIFF measurements in allergy diagnostics and treatment

Spring is just around the corner, it’s cold and wet outside, your nose has been running for days and you wonder, Is this an infection or an allergy?

Allergies can develop at any age, stay with you for a lifetime or change in the course of time. They can also have genetic causes, since individuals with a family history of allergies are at greater risk of developing an allergy.

Preventing allergies is a challenge, but there are a few steps one can take to reduce the risk: nursing infants, avoiding second-hand smoke and minimising exposure to potential allergens. Immunotherapy research, which aims to elevate the immune system’s tolerance of allergens, is also yielding promising approaches to preventing and treating allergies in the future. As soon as an allergy has been diagnosed, treatment is geared toward reducing symptoms and avoiding exposure to allergens. This can involve the use of antihistamines, nasal sprays, eye drops or, in severe cases, epinephrine injections.

Progression of an Allergic Reaction

When first exposed to an allergen, the immune system of a sensitive individual responds by forming specific antibodies, primarily immunoglobulin E (IgE). These antibodies bind to mast cells, basophilic granulocytes and eosinophils in the tissue and to certain immune cells in the blood.

When the immune system comes into contact again with the same allergen, existing IgE antibodies will bind to the corresponding sites on the mast cells, basophilic granulocytes and eosinophils, sensitising these cells to the allergen.

If the allergen encounters the IgE antibodies again, it will bind to them and trigger a reaction in the mast cells, basophilic granulocytes and eosinophils, triggering a coordinated release of inflammatory mediators, including histamine, leukotrienes and cytokines. These produce a variety of symptoms typical of an allergic reaction, such as itching, swelling and shortness of breath, to name just a few. Eosinophils play a special role here, because, in addition to modulating inflammatory reactions, they also react to allergic processes and protect specific tissues.

Once the allergen has been eliminated or the reaction has been stopped through some other means, the activity of the mast cells, basophilic granulocytes and eosinophils slows down and the inflammatory response tapers off. This can be accomplished through antihistamines or other medications that block the effects of inflammatory mediators.

Types of Allergies

Allergies can be broken down into various types that each give rise to different mechanisms and immune responses. This classification system is based on the specific immunoglobulin types involved in the reaction, as well as on the immunological processes underlying the reaction. The following are the four main types of allergic reactions:

Type I: Immediate Reaction (IgE mediated):

In type I allergies, the immune system reacts to an allergen immediately. Immunoglobulin E (IgE) antibodies play a key role here. Following repeated exposure to the allergen, IgE antibodies bind to mast cells and to basophilic granulocytes. When the immune system encounters the allergen again, it releases histamine and other inflammatory mediators, leading to typical allergy symptoms, such as a rash, itching, swelling of the mucous membranes, shortness of breath and, in severe cases, anaphylaxis.

Type II: Cytotoxic Type (Antibody Mediated):

IgG and IgM antibodies play a role in the type II mechanism, where they bind to target cells that present the allergen on the cell surface. As a result, the immune system identifies the target cells as foreign and destroys them. This mechanism can play a role in the pathogenesis of autoimmune diseases and allergies to medications.

Type III: Immune Complex Type (Immune Complex Mediated)

Type III allergies involve the formation of immune complexes comprising allergens and specific antibodies such as IgG, IgA and IgM. These immune complexes can deposit in a variety of tissues, leading to an inflammatory response. Typical manifestations include Arthus reactions, serum disease and the formation of immune complexes in blood vessels, joints or kidneys.

Type IV: Cell-Mediated Late-Type Allergy:

This type is characterised by a delayed response, typically within 24 to 72 hours following contact with the allergen, and is mediated by specialised immune cells, primarily T-cells. Following contact with the allergen, T-cells activate other immune cells, which set inflammatory processes in motion. This type is characteristic of contact allergies such as allergic contact dermatitis.

Measuring IgE levels in the blood can help physicians estimate the severity of an allergic reaction and assess the risk of severe allergic reactions such as anaphylaxis. Individuals with elevated IgE levels in their blood may be more sensitive to certain allergens and therefore need more intensive monitoring and treatment.

Generally speaking, IgE antibodies play an important role in the immune system’s response to allergens and are an important factor in diagnosing and classifying allergic reactions.

The Importance of 5-DIFF Analysis

Eosinophil analysis plays an important role as well. Haematological analysers that can perform 5-part differential counts are becoming an increasingly common part of point-of-care testing, where they provide a fast, detailed count of the various blood cells, including white blood cells such as eosinophils and basophilic granulocytes.

The use of haematological analysers offering 5-part differential counts allows physicians and other medical professionals to diagnose allergies faster and more accurately. These instruments also serve as an efficient tool for monitoring the progression of an illness and for assessing the efficacy of treatment strategies.

The ability to characterise allergic reactions at the cellular level is critical for developing personalised treatments and for improving the quality of life for patients with allergic diseases. In this respect, haematological analysers that can perform 5-part differential counts have an important role to play in optimising clinical approaches and improving health care for patients with allergies.

By enabling precise characterisation of immune responses, incorporating 5-DIFF analysis into haematological analysers has improved the diagnosis and treatment of allergies. These advances, along with the development of biologics, offer promising opportunities for improving the quality of life of individuals with allergic diseases.