Intralymphatic immunotherapy in allergic rhinitis : evaluating safety, efficacy and mechanisms

Abstract

Allergic rhinitis (AR) deprives work capacity, social activities and quality of life, and costs the Swedish society about €1.3 billion annually. Allergen-specific immunotherapy (AIT) amends the symptoms and improves the course of the disease. The symptom ameliorating effects last several years after the discontinuation of treatment. The golden standard for immunotherapy of AIT is subcutaneous administration but during the last decade sublingual immunotherapy has become common. Both forms of AIT are underused due to the lack of knowledge about the treatments among physicians, lack of access to the treatment and inconvenience for the patients. Intralymphatic immunotherapy (ILIT) is an emerging form of AIT, which requires only 3 injections during a period of 8 weeks. The aim of this thesis was to evaluate the intralymphatic route by using different treatmentprotocols and to characterize immunological signs of tolerance development.

In paper I, asthmatic young adults were treated in a randomized double-blind placebo-controlled (RDBPC) trial with three intralymphatic injections of birch or grass allergen in doses of 1000 SQ-U, or placebo. The active group returned the next year for a booster injection. The treatment was safe, even in patients with mild asthma. The use of symptom relieving medications at the pollen season was reduced the first and the second year after treatment. The allergen specific IgG4 antibodies were increased 6-9 months after treatment. The asthma symptoms could not be improved among well-treated patients. In paper II, polysensitized patients received ILIT for both birch and grass induced AR in a RDBPC trial, with doses of 1000 SQ-U each, in three injections. The treatment was safe, even with two allergens given simultaneously. The rhinoconjunctivitis symptoms after a nasal provocation test were improved 6-9 months after treatment and the use of symptom relieving antihistamines and/or nasal steroid spray was reduced. The timothy specific IgG4-levels, regulatory T-cells (Tregs) and Th1 type of T-cells were increased in blood and the effector memory T-cells were increased in the lymph nodes after treatment. In paper III, ILIT in up-dosing schedules were evaluated in two RDBPC trials. In ILIT after SCIT-10 000, patients that had recently received SCIT for grass AR, were treated with 1000- 3000- 10 000 SQ-U of grass allergen, with one-month intervals. The treatment was safe. The combined symptoms and medication scores (CSMS) were improved during the pollen season after treatment and the timothy specific IgG4 levels were increased. In ILIT de novo- 3000, patients with grass induced AR without previous AIT were recruited. The dose-escalation was safe up to 3000 SQ-U, but serious anaphylactic reactions occurred at 5000 SQ-U. The patients that were treated with the modified protocol 1000-3000-3000 SQ-U did not improve the AR symptoms at pollen season and had no clear signs of beneficial immunologic changes in blood or lymph nodes. In paper IV, the patients that were treated with active ILIT 5-6 years previously in paper II, returned for an open follow-up and were compared to a non-AIT treated control group. The symptoms at NPT were unchanged, but the CSMS at the pollen season was lower compared to in the control group. Timothy specific IgE levels had decreased markedly compared to before treatment, IgG4 was still slightly elevated and the lymph node samples displayed increased levels of memory T-cells.

In summary, ILIT with 1000 SQ-U was safe with mild asthma and when given with two allergens concomitantly. Up-dosing to 10 000 SQ-U was safe among previously SCIT-treated patients, but dose-escalation to 5000 SQ-U induced anaphylaxes in de-novo patients and should not be performed. The AR symptoms were improved after 1000 SQ-U and after up-dosing to 10 000 SQ-U among SCIT-treated patients, but up-dosing to 3000 SQ-U failed to improve the clinical symptoms in previously unvaccinated patients. Early immunological changes included increases in timothy specific IgE and IgG4 levels, Treg and Th1 levels in blood and an increase in the number of EM T-cells in lymph nodes. Long term changes noted were reduced specific IgE levels in blood and an increased number of memory T-cells in lymph nodes, as signs of a possible long-term treatment effect.