Possible sources of Bermuda grass sensitization in Timothy grass allergic subjects

Clinical symptoms and biomarkers of Bermuda grass-induced allergic rhinitis using the nasal allergen challenge model

BACKGROUND

Bermuda grass is a prevalent allergen that flourishes in tropical climates. Its exposure is traditionally believed to be low in Ontario due to the colder environment. However, high sensitization rates have been observed in Kingston, Ontario.

OBJECTIVE

We sought to investigate whether its allergens can provoke allergic rhinitis (AR) symptoms in sensitized participants from south-eastern Ontario and determine if nasal allergen challenge (NAC) model is appropriate to study Bermuda grass-induced AR.

METHODS

Twenty-one participants sensitized to Bermuda grass and 12 nonallergic participants completed a titrated NAC with increasing allergen concentrations at a screening visit. Total nasal symptom score (TNSS) and peak nasal inspiratory flow were collected before allergen exposure and 10 minutes after delivery of each concentration. Twelve participants with a Bermuda grass allergy who met the qualifying criteria (TNSS ≥ 8 and peak nasal inspiratory flow fall ≥ 50%) and 11 nonallergic controls returned for single-dose NAC visit.

RESULTS

At titrated NAC, 19 of 21 sensitized participants met the criteria of positive allergic response when challenged. During single-dose NAC, participants with allergy had significantly greater TNSS between 15 minutes and 3 hours after NAC than controls. Likewise, allergic participants had a significantly increased number of nasal lavage eosinophils at both 1 and 6 hours after NAC. Bermuda grass-specific immunoglobulin E was significantly increased in Bermuda grass allergic participants at NAC than screening visit.

CONCLUSION

Although Bermuda grass is a non-native allergen in Ontario, it can induce AR symptoms in sensitized participants, and the NAC model is appropriate to study Bermuda grass-induced AR.