Statistical analysis will be with non-parametric statistics taking into account treatment effect baseline values and visit number. Inclusion of 20 participants per group will give greater than 90% power (p=0.05) to detect a 40% reduction in the early phase response (EPR) after nasal challenge (AUC of the TNSS in the first 60 minutes after challenge, a 40% reduction in the skin LPR, and a 50% increase in grass pollen allergen specific immunoglobulin G4 (IgG4) for AIT vs. placebo.