The aim of this study is to investigate the immunomodulatory potential of Isolated Plasmacytoide Dendritic Cells (pDCs) and Regulatory T-cells (TREGs) isolated with clinical grade magnetic bead isolations techniques (MACS®) on the antigen presenting cell-induced proliferation of lymphocytes after allergen uptake in an in vitro cell culture system.

pDCs as well as TREGs will be co-incubated with generated allergen presenting cells, lymphocytes, and allergen. For in vitro experimentation immune cells will be collected from blood of grass mix or house dust mite sensitized atopic/asthmatic patients.

Inclusion Criteria:

• Male subjects suffering from allergic rhinitis and/or allergic asthma against timothy grass pollen (phleum pratense) and/or house dust mite.
• age 18-60 years,
• Nonsmokers or smokers with a history of less than 1 pack years who have not smoked within the last 12 months.
• Positive skin prick test for timothy grass pollen (phleum pratense) and/or house dust mile within 12 months
• Able and willing to give written informed consent
• Hemoglobin ≥135 g/l
• Hematocrit ≥ 0,40
• Body weight ≥ 50 kg and Body Mass Index (BMI) within the range 19-32 kg/m²

Exclusion Criteria:

• History of lower respiratory tract infection and /or exacerbation of asthma within four weeks prior to the informed consent visit
• Febrile illness within four week before the trial examination
• Administration of oral, injectable, or dermal corticosteroids within the last 8 weeks or intranasal and/or inhaled corticosteroids within the last 4 weeks.
• Intake of methylxanthines, antihistamines, antileukotrienes, oral cromolyn sodium, or oral nedocromil sodium
• Past or present disease, which as judged by the investigator, may affect the outcome of this trial. These diseases include, but are not limited to, cardiovascular disease, malignancy, hepatic disease, renal disease, hematological disease, neurological disease, endocrine disease, or pulmonary disease (including but not confined to chronic bronchitis, emphysema, tuberculosis, bronchiectasis or cystic fibrosis).
• Specific immunotherapy (SIT) within the last two years prior to screening
• Participation in another clinical trial 30 days prior to enrollment
• Donation of more than 500 ml of blood in the preceding 9 weeks before the trial-examination
• Hemoglobin below the normal lower limit
• History of drug and/or alcohol abuse or dependence within 12 months of the trial
• Risk of non-compliance with trial procedures
• Suspected inability to understand the protocol requirements, instructions and trial-related restrictions, the nature, scope, and possible consequences of the trial
• Patient is tested human immunodeficiency virus (HIV)-1/2Ab, hepatitis B surface antigen (HBsAg), or hepatitis C virus antibodies (HCV-Ab) positive