Immunotherapy was first reported in 1911 and involved repeated allergen injections to induce tolerance. Each allergen must be treated individually, except for instances of  cross-reactivity where one is similar enough to another to induce tolerance for that antigen. Minor modifications to subcutanceous (injection) immunotherapy (SCIT) have been made over the years, but it has been the dominant form of therapy in the United States for over a century.

 

Unfortunately, SCIT is not without risks and disadvantages. Years of weekly injections can be inconvenient,  and local skin reactions with itching, shortness or breath, and even serious anaphylactic reactions can occur. Very rarely death has been reported, usually in asthmatics. Current recommendations include a 20 minute observation following injections given only in a physician's office.  Given these limitations, investigators developed safer, more convenient forms of immunotherapy.

 

As early as 1913, alternatives were proposed, with nasal and oral immunotherapies showing the greatest promise. Oral therapy includes the direct swallow and the sublingual (under the tongue) methods (SLIT).   In 1998 the World Health Organization approved both sublingual and nasal methods as viable alternatives to injections.  Nasal immunotherapy has proven to be difficult and less well-received than oral methods. Oral immunotherapy with immediate swallowing is less effective than SLIT in most studies. 

 

Immunotherapy by any method is thought to work primarily through three mechanisms 1) antibody action  (blocking antibodies) 2)  inflammatory chemicals and 3)cellular inflammatory responses (White blood cells). SLIT may use different mechanisms of action than those of SCIT.  

 

The effectiveness of SLIT may relate to the duration of contact and a critical interaction with the immune cells of the floor of the mouth. Minimal absorption occurs, but  there is persistence of antigen in the mouth for long periods.   Antigen that is swallowed is minimally absorbed and completely degraded in theintestines. We feel it is critical to watch the clock when taking a dose of SLIT to ensure a 2 minute exposure.

 

The effectiveness of SLIT has been based on patient reports of symptom decrease and reduced dependency on medications.    Treatment duration of at least two years appears minimally necessary, but we recommend 3-5 years as with injection therapy.  Pollens seem to be most effective with dust mite and pet danders requiring longer durations of treatment. We believe effects begin in about six months.

 

Sublingual immunotherapy is made from the same antigen extracts used for injections.  This is an "off-label" use of allergen extracts.  Off-label use of medications is very common in medicine, with between 25%-40% of all medications used for indications not approved by the Food and Drug Administration (FDA).

 

There have been only mild reactions noted such as oral itching, headache, runny nose, hives, constipation or other gastrointerstinal side effects. To date, only a few episodes of anaphylaxis associated with SLIT have been reported. Two of these were with food allergy SLIT and one with Latex SLIT. No reports have been with inhalant allergens and there have been no deaths. 

 

We follow the American Academy of Otolaryngic Allergy dosing.recommendations whereby all patients are started at a standard concentration and advanced over twelve weeks to the maximum strength dosage.  This is continued daily for one year. If  no response is seen by a year, therapy is stopped. For patients responding to therapy, it  is continued for 3-5 years before trying to terminate.  After 5 years a small percentage of patients will not develop lasting tolerance and may require longer therapy.

 

 

In 2005, the Asthma and Allergy Foundation of America performed a survey of allergy patients that asked for the important features of an allergy medication.  These were the features that were important to 50% or more of the respondants, and how these features relate to SLIT.

 

 

1.  Long lasting symptom relief               Immunotherapy is the only

                                                                       lasting allergy treatment

 

 

 

2.  Rapid relief of symptoms                    Generally 6 months to see effects

 

 

 

3.  Minimal side effects                             Less side effects than allergy shots

                                                                       Minimal risk for anaphylaxis

                                                                       Rare tingling in mouth

 

 

 

4.  No sedation/drowsiness                     None

 

 

 

5.  Covered by insurance                          No, but cost may be 

                                                                       comparable with insurance

                                                                       copays

 

 

6.  Inexpensive                                            Indirect cost savings

                                                                    

7. Safe with other medications                Yes, except for "Beta Blockers"

 

 

 

8.  Easy to take                                            Home based, once a day,

                                                                       self-administered

 

 

 

9.  Non-habit forming                                 Not addictive, but should be

                                                                       a habit

 

 

 

10.  Dosing flexible (as needed)             Best if used regularly

 

 

 

11.  Targets specific symptoms              Targets all symptoms of allergy

 

 

 

12.  Steroid-free                                          Yes