Objective of this trial is to demonstrate the safety and tolerability of different dose combinations of MPL and grass pollen allergen and to identify the highest combination of MPL and grass pollen allergen which is safe.~Other objectives are to investigate the pharmacodynamics and efficacy of MPL and grass pollen allergen.
Safety and tolerability of different dose combinations of MPL and grass pollen allergen and to identify the highest combinations of MPL and grass pollen allergen which is safe.~Pharmacodynamics and efficacy of MPL and grass pollen allergen.