The aim of the study is to establish the maximum tolerated dose of PURETHAL Mites that is achieved by 90% of the patients with less than 20% of the injections giving rise to a swelling of > 5 cm and the optimal regimen to reach this maximum dose will be determined.

The tolerability and safety of three different initial treatment regimens PURETHAL mites in patients with allergic rhinitis / rhinoconjunctivitis induced by house dust mites will be evaluated and the optimal regimen to reach the maximum tolerated dose will be determined. The maximum intended dose is a 4-fold dosage compared to the currently used maintenance dose of PURETHAL Mites. The tolerability and safety of the injections will be examined by means of determining the early and late local and systemic reactions. In addition, short-term efficacy of this high dose PURETHAL mites will be determined by means of the Clinical index score (CIS) and two surrogate efficacy markers; the conjunctival provocation test (CPT) and serum levels of allergen specific immunoglobulins (IgG and IgE). These efficacy parameters are purely indicative and not decisive for the further clinical development of PURETHAL Mites.

Inclusion Criteria:

1. Patients with perennial rhinitis or rhinoconjunctivitis, with or without mild asthma (FEV1 > 70%) for at least 2 years. with allergic symptoms related to HDM
2. Positive CPT test to HDM Der p, dose ≤10,000 AUeq/ml
3. Positive SPT to HDM Der p or Der f (mean wheal diameter ≥ 3mm)
4. Specific serum IgE-test (ssIgE > 0.7 U/ml) for HDM
5. Age ≥ 18 years
6. Written informed consent given

Exclusion Criteria:

1. Patients with concomitant sensitization i.e. positive SPT (mean wheal diameter ≥ 3 mm) to other allergens than HDM should not be included if they have clinical symptoms at the time of inclusion, related to the other allergen
2. Patients sensitized to pets should not be included if they live together with these pets or have clinical symptoms
3. Immunotherapy (including sublingual) with HDM within the last 5 years
4. Immunotherapy (including sublingual) during the study period
5. Chronic asthma or emphysema, particularly with a FEV1 ≤ 70% of predicted value or use of inhalation corticosteroids
6. Serious immuno-pathologic diseases or malignancies (including auto-immune diseases, tuberculosis)
7. Symptomatic coronary heart diseases or severe (even under treatment) arterial hypertension
8. Diseases with a contra-indication for the use of adrenaline
9. Patients who are using other aluminium preparations, e.g. antacids
10. Severe kidney disease
11. Use of systemic steroids
12. Treatment with systemic and local Beta-blockers or immunosuppressive drugs
13. Active infection of the target organs (nose or eyes)
14. Severe atopic dermatitis in case systemic immunosuppressive medication is used
15. Participation in a clinical study with a new investigational drug within the last 3 months
16. Pregnancy, lactation or inadequate contraceptive measures (adequate contraceptive measures will be the use of a contraceptive device or -pill)
17. Alcohol- or drug abuse
18. Lack of co-operation or severe psychological disorders
19. Institutionalisation by official or judicial order