LYmph Node eXamination in Cat Allergen Immunotherapy

Sixteen eligible cat-allergic participants will be accrued in the study. Eight participants who have been on subcutaneous immunotherapy (SCIT) at maintenance dosing for at least 1 year will be assigned to the SCIT cohort, and 8 participants who have never been on cat immunotherapy will be assigned to the No immunotherapy (IT) cohort. Participants will undergo intradermal cat allergen challenge in bilateral upper arms at baseline (Day 1), will undergo axillary lymph node and peripheral blood sampling at Day 4, and axillary lymph node, peripheral blood, and adenoid and nasal sampling at Week 3. The primary objective is to determine the number of analyzable cells from axillary lymph node fine-needle aspiration 3 days and 3 weeks after intradermal cat allergen challenge in two cohorts of cat-allergic participants: those undergoing cat allergen immunotherapy and those who are not receiving this treatment