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Specific immunotherapy, commonly known as desensitization, is one of the methods of treating allergic diseases. The essence of specific immunotherapy is to extinguish the excessive response of the immune system to selected allergens. Find out how specific immunotherapy works, what are the indications and contraindications for specific immunotherapy, how does it work and what are the side effects of specific immunotherapy?

Contents:

  1. Specific immunotherapy - what is it?
  2. Specific immunotherapy - principle of operation
  3. Specific immunotherapy - course and duration
  4. Specific immunotherapy - recommendations
  5. Specific immunotherapy - treatment effects
  6. Specific immunotherapy in children
  7. Specific immunotherapy - side effects
  8. Specific immunotherapy - contraindications

Specific immunotherapyalleviates the symptoms of allergic diseases by developing immunological tolerance to specific antigens. The effectiveness of specific immunotherapy has been proven in the treatment of many allergic diseases, such as allergic rhinitis, bronchial asthma or allergy to insect venom.

Specific immunotherapy is not merely symptomatic treatment. Due to the modulation of the processes underlying allergy, specific immunotherapy is one of the methods of causal treatment.

Specific immunotherapy - what is it?

Specific immunotherapy is designed to inhibit the over-reactivity of the immune system, leading to the appearance of allergy symptoms. The essence of specific immunotherapy is the administration of increasing doses of allergens to which a given patient is allergic.

Contact of the immune system with antigens regularly administered in the form of subcutaneous injections or sublingual tablets allows the development of immunological tolerance to them.

At the beginning of specific immunotherapy, allergen vaccines are given frequently (usually weekly). Over time, the rate of vaccine intake decreases; in maintenance therapy, they are used every few weeks. The entire treatment process with specific immunotherapy usually takes several years (3-5).

Regularity is one of the key conditions for the effectiveness of specific immunotherapy. Although the prospect of long-term therapy mayseem burdensome, it is worth remembering that specific immunotherapy is the only method of causal treatment of allergies.

Scientific research has shown that specific immunotherapy not only alleviates the symptoms of allergic diseases, but also inhibits the progression of allergies towards more and more serious manifestations.

Specific immunotherapy - principle of operation

Specific immunotherapy is effective in treating the so-called IgE-mediated allergies. These are hypersensitivity reactions caused by the presence of specific IgE antibodies in the patient's blood.

These antibodies are directed against specific allergens (e.g. house dust mites, grass pollen, cat dander). After an allergic person comes into contact with the allergen, it is bound by circulating antibodies in the blood. The immune system recognizes the allergen as a threat and aims to eliminate it.

The binding of an allergen to antibodies against it is a "trigger factor", triggering an intense response from the immune system.

The immune cells (mainly mast cells and basophils) are stimulated. These cells release a variety of chemicals (including histamine) and inflammatory molecules that trigger allergy symptoms.

At this point, the patient begins to experience typical ailments: sneezing and tearing, conjunctival redness, runny nose, itchy skin and shortness of breath.

Specific immunotherapy influences the processes underlying allergies in a multidirectional way. One of the key phenomena in the immune system of allergic patients is the excessive activation of Th2 lymphocytes. These are cells that stimulate the production of IgE antibodies, responsible for the development of allergies.

Additionally, Th2 lymphocytes produce molecules that involve many other cells in an allergic reaction. It is currently believed that one of the basic mechanisms of action of specific immunotherapy is the suppression of the immune response involving Th2 lymphocytes.

Additionally, the so-called regulatory T cells that quench the allergic and inflammatory response. Specific immunotherapy also produces antibodies other than IgE (mainly IgG4), which also contribute to the alleviation of allergy symptoms.

Specific immunotherapy - course and duration

  • subcutaneous immunotherapy

The specific immunotherapy scheme is selected individually for each patient. The course of therapy depends on the patient's age, clinical condition and response to treatment.

Classical specific immunotherapy consists of two stages:induction phase and maintenance phase.

  1. The essence of the first (induction) phase is to develop tolerance to the administered allergens.
  2. The second (maintenance) phase is designed to maintain the effect achieved in the first phase.

In the induction phase of immunotherapy, the patient receives increasing doses of the allergen in the form of subcutaneous injections. Vaccines are usually administered at a frequency of 1 / week. The first phase of specific immunotherapy usually lasts from 2 to 6 months. This is the period that requires the greatest involvement of the patient - regular, weekly visits are necessary to achieve the beneficial effects of immunotherapy.

The maintenance phase of specific immunotherapy is associated with a reduction in the frequency of medical visits. Maintenance doses of allergen vaccines are usually given at 4-8 week intervals. The entire treatment process with specific immunotherapy takes several (usually 3-5) years.

After each administration of a specific immunotherapy dose, it is necessary to stay under the doctor's supervision for a short time (about 30 minutes). The purpose of observation is to quickly prevent possible side effects that may appear as a result of administration of the vaccine.

The office, where specific immunotherapy is performed, is always equipped with the means enabling a quick reaction in the event of undesirable symptoms.

Depending on the type of allergen the patient is allergic to, the course of specific immunotherapy can be modified. A good example is allergy to seasonal allergens, which include, among others grass pollen.

In such a case, specific immunotherapy can be performed in the period preceding the pollen season. Vaccines are suspended during periods of high pollen concentration. The next cycle of immunotherapy is necessary only before the start of the next pollen period

  • sublingual immunotherapy

The inconveniences related to the subcutaneous administration of vaccines (the need for frequent medical visits, reluctance of patients to receive injections) initiated research into other ways of administering specific immunotherapy. Their result was the development of sublingual allergen vaccines (SLIT - Sublingual Immunotherapy).

Sublingual immunotherapy is associated with a lower risk of adverse side effects. For now, however, this method of immunotherapy is less widely used than subcutaneous immunotherapy.

The effectiveness of sublingual immunotherapy has been proven in relation to selected allergens. Currently, sublingual immunotherapy is used in selected treatment casesallergic rhinitis and bronchial asthma.

Research into the effectiveness of sublingual immunotherapy in other allergic conditions is ongoing.

  • accelerated scheme immunotherapy

In some specific immunotherapy regimens, it is possible to accelerate the first phase of treatment. Allergen vaccines are then administered more than once a day. Thanks to this, it is possible to develop tolerance to a given antigen faster.

In Poland, accelerated specific immunotherapy regimens are used, for example, in the treatment of patients allergic to insect venom. However, it is worth knowing that increasing the frequency of taking subsequent doses is associated with an increased risk of side effects of specific immunotherapy.

For this reason, accelerated desensitization schedules are only used under conditions of constant patient supervision.

Specific immunotherapy - recommendations

Specific immunotherapy is used in the treatment of allergic diseases such as: allergic rhinitis, allergic conjunctivitis, bronchial asthma or allergy to hymenoptera venom.

Specific immunotherapy is - as the name suggests - directed against a specific allergen causing allergy symptoms in a given patient.

In order to refer a patient for treatment with specific immunotherapy, it is necessary to identify the allergens to which the patient is allergic. The relationship between sensitization and the occurrence of disease symptoms should also be demonstrated (contact with a given allergen must cause allergic symptoms).

Qualification for treatment requires a detailed medical history and tests confirming sensitization (allergen skin tests, determination of specific IgE antibodies in the blood).

It is also worth remembering that allergic diseases are usually treated pharmacologically in the first place. It is only the insufficient effectiveness of pharmacotherapy, the necessity of its chronic use or the presence of side effects that the patient is referred for treatment with specific immunotherapy.

Specific immunotherapy - treatment effects

Among allergic diseases with a proven IgE-dependent mechanism of formation, specific immunotherapy brings the most beneficial effects in the treatment of allergic rhinitis, conjunctivitis, bronchial asthma and allergy to hymenoptera venom.

Research on the use of specific immunotherapy in other allergy-related diseases such as atopic dermatitis and allergies is ongoingalimentary.

  • specific immunotherapy and allergy to insect venom

Patients allergic to Hymenoptera venom may develop symptoms of a life-threatening anaphylactic shock as a result of the stings: drop in blood pressure, shortness of breath, increased heart rate and dizziness.

Specific immunotherapy is a method that significantly reduces the risk of this type of reaction. The effectiveness of specific immunotherapy in the treatment of allergy to Hymenoptera venom is estimated at 90%.

Only about 10% of patients after undergoing a full course of immunotherapy are still at risk of developing symptoms of anaphylaxis. Nevertheless, it is much milder in these patients. Insect venom allergy is a disease in which specific immunotherapy brings the greatest effects.

  • specific immunotherapy and allergic rhinitis

Specific immunotherapy in the treatment of allergic rhinitis gives the best results in patients allergic to a narrow group of allergens. A better response to treatment occurs in the case of seasonal allergic rhinitis (so-called hay fever), and a weaker response - in the case of year-round rhinitis.

The greatest effectiveness of specific immunotherapy is observed in the case of allergy to pollen of grasses and other plants. Slightly weaker effect is achieved by desensitizing to pet hair and house dust mites.

In order to maintain the beneficial effects of immunotherapy, it must be used for a long time (according to research, at least 3 years).

  • specific immunotherapy and bronchial asthma

Specific immunotherapy has proven beneficial effects in the treatment of bronchial asthma: it reduces the severity of the symptoms of the disease, alleviates bronchial hyperreactivity, and reduces the amount of medications necessary to use.

Research has also shown that the use of specific immunotherapy may prevent the onset of bronchial asthma in patients with an inherited tendency to allergic reactions (the so-called atopy).

  • specific immunotherapy and atopic dermatitis

In the last century, a series of studies was launched to establish the role of specific immunotherapy in the treatment of atopic dermatitis. Their results showed that the use of specific immunotherapy may be beneficial in AD cases caused by sensitization to specific inhaled allergens.

Specific immunotherapy is currently used as one of the additional treatments for atopic dermatitis. Of primary importance in the treatment of AD is pharmacotherapy combined with appropriate skin care.

  • specific immunotherapy and food allergies

The beneficial effects of treating some allergic diseases with specific immunotherapy have led to attempts to use this therapy in the treatment of food allergies. This variant of specific immunotherapy would rely on the oral intake of increasing amounts of nutrients to which the patient is allergic.

So far, specific immunotherapy in the treatment of food allergies is an experimental method and is not used routinely. The greatest limitation is the high risk of severe side effects and the lack of evidence of long-term effectiveness of this type of therapy.

Specific immunotherapy in children

Is specific immunotherapy safe for children? Definitely yes, and if there are indications for immunotherapy, its initiation should not be delayed. The lower age limit for the initiation of specific immunotherapy is the child's 5th year of life.

Children prone to allergic reactions often show symptoms of the so-called The "allergic march". It is a series of allergic diseases that appear successively at different stages of a child's life.

At an early age, these may be food allergies and symptoms of atopic dermatitis. Later on, the baby may show symptoms of allergic rhinitis. The last stage in the development of the "allergic march" is bronchial asthma.

This sequence of diseases does not have to occur in every allergy sufferer, however, the occurrence of one of them increases the risk of the occurrence of subsequent stages of the march. Specific immunotherapy, in addition to alleviating the current symptoms of allergies, reduces the risk of progression towards more and more severe allergic diseases.

For this reason, the decision to start it should be made early enough. Then the chance of beneficial changes in the immune system, reducing the tendency to allergy, is the highest.

Specific immunotherapy - side effects

Specific immunotherapy is considered a relatively safe method of treatment, and serious side effects are rare. The most common complication of subcutaneous injection of an allergen vaccine is local redness, swelling and itching at the injection site.

More serious systemic reactions, such as a drop in blood pressure or shortness of breath, appear much less frequently (about 1-5% of patients). The most serious and the rarest complication of specific immunotherapy is anaphylactic shock.

Allergen vaccines are always administered in properly prepared placesto treat patients who may experience such complications.

The risk of serious complications is lower with sublingual immunotherapy. This form of immunotherapy is associated with the risk of side effects related mainly to the site of administration (burning in the mouth, swelling and burning sensation of the tongue, lips).

Complications within the digestive tract (abdominal pain, vomiting, diarrhea) are less frequently observed. Severe complications in the form of anaphylactic shock are extremely rare in sublingual immunotherapy.

Specific immunotherapy - contraindications

Specific immunotherapy, as a treatment method with a relatively low risk of serious side effects, has few absolute contraindications to its use.

Specific immunotherapy is not used in the advanced stages of severe systemic diseases such as heart failure, unstable angina or uncontrolled hypertension.

Also, advanced, poorly controlled bronchial asthma is a contraindication to the use of specific immunotherapy.

The above limitations are due to the fact that patients with this type of chronic disease have an increased risk of severe side reactions resulting from the administration of allergen vaccines.

The diseases that limit the qualification of patients to specific immunotherapy also include congenital and acquired immunodeficiencies (eg in the course of treatment of neoplastic diseases). These types of diseases cause disorders of the immune system, which contribute to the reduction of the effectiveness of specific immunotherapy.

Another group of patients with relative contraindications to specific immunotherapy are people taking certain groups of cardiovascular drugs (beta-blockers, ACE-inhibitors).

Research has found a higher frequency of severe systemic symptoms with immunotherapy. However, these are only relative contraindications, requiring individual consideration of the benefit-risk balance for each patient.

For example, in people allergic to Hymenoptera venom, each sting can carry a direct threat to life. The risk of such severe complications is much greater compared to the side effects of immunotherapy.

For this reason, in selected cases, specific immunotherapy is performed despite the patient's relative contraindications.

At this point, it is also worth mentioning the age criterion of qualification for specific immunotherapy. Behindthe lower age for treatment with this type of treatment is considered to be 5 years old. There are no hard and fast rules as to the maximum age limit for patients.

Nevertheless, the greatest effectiveness of specific immunotherapy is observed in young patients at the early stages of the development of allergic diseases.

Read also: Immunotherapy - what is it? What is immunotherapy?

About the authorKrzysztof BialaziteA medical student at Collegium Medicum in Krakow, slowly entering the world of constant challenges of the doctor's work. She is particularly interested in gynecology and obstetrics, paediatrics and lifestyle medicine. A lover of foreign languages, travel and mountain hiking.

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Immune system