Intralymphatic immunotherapy induces allergen specific plasmablasts and increases tolerance to skin prick testing in a pilot study.

BACKGROUND Allergen Immunotherapy is a promising treatment of allergy. Seven patients with rhinoconjunctivitis to grass allergen were treated with intralymphatic immunotherapy (ILIT) to explore whether this treatment could be performed. Effect of treatment was assessed as change in symptom medication score, response in skin prick test and nasal allergen provocation. ILIT deposits allergen in an inguinal lymph node to elicit a strong immune stimulus. This allowed us to monitor appearance of allergen specific plasmablasts 7 days after allergen injection. FINDINGS In an open trial of seven patients with a history of symptomatic allergic rhinoconjunctivitis due to grass pollen, three injections of allergen into inguinal lymph nodes were performed with monthly intervals. Allergen injections induced grass allergen specific plasmablasts expressing other isotypes than IgE after 7 days, induced a trend toward improvement in symptom and medication score and rhinoconjunctivitis-related quality of life during the grass pollen season 2013 and significantly raised the threshold in nasal allergen challenge and titrated skin prick testing. Mild side-effects were recorded after 3 of the 21 of injections (14 %). CONCLUSIONS This pilot study shows that ILIT may induce allergen specific plasmablasts, and confirms an effect on provocation of mast cells in skin and nasal mucosa during the ensuing winter.