Although these topical routes of administering allergen are generally regarded as safe and not likely to cause adverse systemic anaphylactic reactions as has been reported for injection based immunotherapy on rare occasions, the problem remains that application of allergen extract to affected tissues such as the nose can elicit allergy symptoms. This can be managed by application of symptomatic treatments such as antihistamines during treatment, but clearly this can result in problems in the successful outcome of a treatment, which may involve many repeated allergen doses. Another problem is the length of treatment. Since the allergic patient has a Th2 skewed response as his primary reaction to allergen, treatment with allergen will have to work against this and hence it requires many doses over a long period of time to achieve a successful desensitization.

CMP is a Th1-steering adjuvant
In light of these considerations, there has been a developing interest in the addition of Th1 adjuvants to allergen preparations in either traditional injection based ASIT or topical ASIT to facilitate the switch away from the Th2 type and induce a state of tolerance in the local affected tissues. For example heat-killed Listeria monocytogenes has been shown to enhance ASIT outcome against peanut anaphylaxis in a canine model. Another class of Th1 adjuvants under development are CpG immunostimulatory DNA sequences based on bacterial DNA, which is highly Th1 inducing. These have shown very promising efficacy in clinical trials against ragweed using injection based ASIT, but are probably unsuitable for topical application.

It is proposed that chitin microparticles is a very useful safe adjuvant to both increase efficacy and decrease the treatment time and with the additional advantage of reducing allergen-treatment side effects produced during allergen specific immunotherapy. The data to date supports the application for the nasal route for CMP/allergen formulations and if the suppression of local allergy symptoms by CMP is sufficient this might be the most logical route to effect a change in allergic rhinitis and asthma. Under clinical supervision, patients would first be treated with CMP nasal spray, followed by CMP+allergen extract. Once a safe protocol is established for the individual patient, he would then continue treatment at home on a daily basis with follow up visits at weekly or monthly intervals. It is expected that such a treatment course might last 1-2 months with a maintenance dose administered at monthly intervals.