The investigators will perform double-blinded placebo-controlled randomized clinical trial which evaluates the efficacy and safety of allergen-specific intralymphatic immunotherapy (ILIT) for allergens including Dermatophagoides farinae (Df), Dermatophagoides pteronyssinus (Dp), cat, and dog that are sensitized and provoke rhinitis-related symptoms in patients with allergic rhinitis (AR), using allergen extracts for allergen-specific immunotherapy (Tyrosine S, Allergy Therapeutic, West Sussex, UK).

After informed consent, subjects will be randomly assigned to ILIT group or placebo group in double-blind manner. In both group, causal allergen or placebo will be injected into inguinal lymph node through guidance by ultrasonography three times with 4-week interval. In ILIT group, initial dose of allergen will be 1,000-fold diluted solution from maximal concentration of allergen extract for subcutaneous immunotherapy (Tyrosine S, Allergy Therapeutic, West Sussex, UK) in volume of 0.1ml. If skin is highly reactive in skin prick test, the initial dose will be 10-fold dilution from maximal concentration where diameter of wheal is less than that of histamine. After the first dose, allergen concentration will be escalated 3-fold at second dose, and 10-fold at third dose if there are no (or mild) local or systemic hypersensitivity reaction. The allergen concentration will not change at second or third dose if there is moderate local or systemic reaction. The allergen concentration will decrease by 10 or 100-fold from previous concentration or further injection will be held if there is severe local or systemic reaction after sufficient explanation and discussion with subjects.

The investigators will evaluate allergic rhinitis symptom score before and 4, 12 months after the initial treatment. Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) and Sino-Nasal Outcome Test (SNOT-20) will be used. Visual analogue scale (VAS) of symptoms including rhinorrhea, sneezing, nasal obstruction, postnasal drip, eye/nose/ear/palate itching, dyspnea, wheezing, chest discomfort as well as urticaria, angioedema, and itching on exposed skin during exposure to causal allergen in daily life will be also evaluated. Skin prick test (SPT), intradermal test (IDT), blood sampling for serum total immunoglobulin E (IgE), allergen-specific IgE, and allergen-specific immunoglobulin G4 (IgG4), nasal lavage for Th1, Th2, and Treg cytokines, and nasal provocation test (NPT) with Df and/or Dp allergen (in subjects whose AR symptoms are provoked by Df and/or Dp) will be also performed before and 4, 12 months after the initial treatment. In addition, the investigators evaluated the change of subjects' recognition of causal allergens, their avoidance, and AIT during this study. Using VAS, subjects were requested to score the rate of agreement with "Allergen provokes allergic symptoms in daily life", "Allergen avoidance can reduce allergic symptoms", "Allergen-specific Immunotherapy (AIT) can reduce allergic symptoms", "I can pay 50,000 Korean Won (KRW)/month for allergen avoidance", "I can pay 100,000 KRW/month for allergen avoidance", "I can pay 200,000 KRW/month for allergen avoidance", "I can pay 150,000 KRW for each injection of ILIT", "I can pay 300,000 KRW for each injection of ILIT", "I can pay 600,000 KRW for each injection of ILIT" before and after SPT/IDT, after NPT, 4 months and 1 year after ILIT.

Adverse events will be recorded and graded according to Muller classification and Ring and Meissner classification.

Inclusion Criteria:

We enrolled subjects who suffered from AR, symptoms of which were provoked by Dp, Df, dog, and/or cat allergen. Concretely, two inclusion criteria should be met.

1. Sensitization should be verified by skin prick test and the level of serum specific IgE measured by ImmunoCAP® (Thermo Fisher Scientific, Uppsala, Sweden).
2. Subjects should complain of AR symptoms during exposure of house dust, dog and/or cat in daily life.

Exclusion Criteria:

1. Uncontrolled or severe asthma according to Global Initiative of Asthma (GINA) guideline including a case in which forced expiratory volume in 1 s (FEV1) was less than 50% of predicted value
2. Significant cardiovascular, hepatic, renal, hematologic, oncologic, or infectious diseases
3. Administration of beta blocker, angiotensin converting enzyme inhibitor, tricyclic antidepressant, immunosuppressant including systemic glucocorticosteroid within last 2 weeks
4. AR caused by other perennial or seasonal allergen
5. Prior history of allergen-specific immunotherapy
6. Rejection or low compliance,
7. Pregnancy or lactation
8. Vulnerable volunteer