Allergen Immunotherapy (AIT) is a fundamental treatment approach for allergic reactions, involving long-term, regular exposure to allergens to modulate the immune system's response. Its primary goal is to reduce patients' hypersensitivity to specific allergens, thereby decreasing the frequency and severity of symptoms. Unlike conventional anti-allergy medications, this therapy can induce long-term immune regulation and may even achieve permanent symptom improvement.
Dessensitization therapy mainly divides into two categories: Subcutaneous Immunotherapy (SCIT) and Sublingual Immunotherapy (SLIT). SCIT involves gradually increasing allergen concentration through subcutaneous injections, while SLIT administers allergens via sublingual tablets or drops. Their mechanisms include inducing regulatory T cell differentiation, increasing IgG blocking antibodies, and modulating Th1/Th2 cytokine balance, ultimately reducing IgE-mediated allergic reactions.
This therapy is primarily used for treating Type I allergic reactions, including perennial allergic rhinitis, seasonal allergic rhinoconjunctivitis, and asthma. For moderate to severe symptoms caused by dust mites, pollen, cat dander, and other specific allergens, when standard medication treatments are ineffective, immunotherapy can be considered. Recent studies also suggest potential efficacy for bee venom allergy and certain drug allergies.
SCIT treatment requires an build-up phase and a maintenance phase. During the build-up phase, injections are given weekly with gradually increasing doses. In the maintenance phase, injections are administered every 4-6 weeks at a fixed dose. The entire course typically lasts 3-5 years. SLIT involves daily sublingual administration of specific allergen extracts, with a longer treatment duration usually 3-5 years. Dose adjustments should be based on allergen test results and symptom responses, with dynamic modifications as needed.
This therapy's unique advantage lies in its disease-modifying effects, which can reduce airway hyperresponsiveness and improve lung function. Long-term follow-up shows that about 70-80% of patients experience symptom relief after completing the course, with evidence suggesting a reduced risk of new allergen sensitization. Compared to conventional medications, its benefits can last for several years and decrease long-term medication dependence.
Potential risks include local reactions such as redness or itching at the injection site, and in severe cases, systemic allergic reactions (anaphylaxis). The severe reaction rate for SCIT is approximately 0.01-0.2%, while oral itching or throat discomfort occurs in about 30-50% of SLIT patients. First injections should be administered in a medical facility with monitoring for at least 30 minutes. Patients should carry an adrenaline auto-injector for emergency use.
Contraindications include uncontrolled severe airway obstruction, cardiovascular diseases, or immune deficiencies. During treatment, live vaccines should be avoided, and it is recommended to pause treatment during early pregnancy. Patients should undergo skin prick tests and serum-specific IgE testing before treatment to confirm allergen types and appropriate dosing.
Combination with antihistamines may alleviate symptoms but does not affect the efficacy of immunotherapy. The use of corticosteroids or anti-IgE monoclonal antibodies may alter treatment outcomes; patients should inform their healthcare provider of all medications they are using. Simultaneous use of allergen-specific immunotherapies (such as sublingual and subcutaneous) should be avoided to reduce risk.
Multicenter randomized controlled trials show that SCIT improves symptoms in pollen allergy patients by 60-70% and can reduce steroid use by 50%. Lung function indices (FEV1) in asthma patients improve by an average of 10-15%. Twenty-year follow-up studies confirm sustained benefits after therapy completion, with some patients experiencing long-term remission of 5-10 years.
Alternatives include antihistamines, nasal corticosteroid sprays, and monoclonal antibody drugs (such as omalizumab). These treatments can quickly relieve symptoms but do not address the root cause. Allergen avoidance measures are effective but difficult to fully implement for dust mites and other environmental allergens. Emerging sublingual therapies and traditional injections have their respective advantages and disadvantages; selection should be based on patient preferences.
Before treatment, patients should undergo allergy skin testing or blood tests to identify specific allergens. Physicians will assess overall health, especially lung and heart function, and check for severe complications. Patients should stop certain antihistamines at least 48 hours prior and avoid alcohol on the day of treatment.
What should I do if I experience redness or itching at the injection site during treatment?Minor redness can be relieved with ice packs for 10-15 minutes and avoiding scratching. If blisters, persistent swelling, or systemic symptoms such as difficulty breathing occur, stop injections immediately and contact your healthcare team. The physician may adjust the dose or prescribe short-term corticosteroids to suppress excessive reactions.
Are there dietary or activity restrictions during treatment?It is recommended to avoid vigorous exercise within 2 hours after treatment to reduce the risk of systemic reactions. Avoid spicy foods and alcohol, as they may trigger allergic symptoms. Light meals and adequate hydration are advised on treatment days to promote metabolic stability.
How often should I follow up after completing treatment?It is recommended to return for follow-up every 3-6 months in the first year after treatment, then annually. Doctors will monitor allergic responses through skin prick tests or serum IgE levels. If symptoms recur, re-evaluation may be necessary to determine if additional treatment or preventive measures are needed.
How long does the long-term protective effect of desensitization last?Studies show that patients who complete more than 3 years of therapy can experience symptom relief lasting 3-5 years. The duration of protection depends on the allergen type and individual immune response. Dust mite immunotherapy generally offers more durable long-term benefits than pollen allergy treatment. Continued avoidance of allergens after therapy can significantly prolong the effect.
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