Allergen immunotherapy

Subcutaneous Subcutaneous immunotherapy (SCIT), also known as allergy shots, is the historical route of administration and consists of injections of allergen extract, which must be performed by a medical professional. Subcutaneous immunotherapy protocols generally involve weekly injections during a build-up phase, followed by a monthly maintenance phase that consists of injections for a period of 3–5 years. The build-up phase involves the patient being administered injections which contain increasing amounts of allergens about one to two times per week. The length of the build-up phase is dependent upon how often injections are administered, but normally ranges from three to six months. After the effective dose is reached, the maintenance phase is implemented, which varies depending upon an individual's response to the build-up phase. SCIT can be used for desensitizations to airborne allergens and insect venoms. Common airborne allergens targeted in SCIT include pollens (of grasses, trees, and weeds), animal danders, molds, and cockroach allergens. Venoms from bees and wasps are often the target of SCIT in patients with severe insect venom allergies. When accounting for a person's age, type of allergen, and severity of allergy, there is a high probability that subcutaneous allergen immunotherapy may provide greater clinical and immunological responses than sublingual allergen immunotherapy. Compared to sublingual allergen immunotherapy, there are no significant differences observed in quality of life. Subcutaneous allergen immunotherapy adverse events vary significantly depending on different allergenic extracts and the application of different allergen immunotherapy schedules. This effectiveness, however, varies depending on the type of allergen. Sublingual immunotherapy is used to treat allergic rhinitis, often from seasonal allergies, and is typically given in several doses over a 12-week period. It works best when given 12 weeks before the start of the pollen season. There are patents issued covering the delivery of allergens via toothpaste. , there are currently clinical trials for a peanut allergy toothpaste. OMIT is not approved by the FDA in the United States. Oral Oral immunotherapy (OIT) involves feeding an allergic individual increasing amounts of a food allergen in order to raise the threshold which triggers a reaction. Long-term, many study participants still experienced mild allergic reactions or needed to regularly consume the allergen to maintain desensitivity. Additionally, oral immunotherapy is known to have an increased risk in the probability of needing epinephrine in patients who take it. Currently, the U.S. Food and Drug Administration has not approved any oral immunotherapy agents for asthma. In January 2020, the FDA approved Palforzia for mitigating "allergic reactions, including anaphylaxis, that may occur with accidental exposure to peanuts." It is the first drug approved for peanut allergies. It will not allow allergic people to eat normal amounts of peanuts, but helps prevent allergies due to accidental eating. Intralymphatic Intralymphatic allergen immunotherapy (ILIT) involves administration of immunotherapy directly into the lymphatic system, which is done by ultrasound guided injections into lymph nodes. Compared to SCIT and SLIT, ILIT is completed faster, over the course of eight weeks, and only involves a total of three injections. This form of immunotherapy is newer than SCIT and SLIT. As of January 2025, ILIT is not an FDA-approved method of allergen immunotherapy and is not widely available as a form of allergen immunotherapy. Currently, ILIT is most commonly offered at academic medical centers, such as The Ohio State University Wexner Medical Center and Washington University School of Medicine in St. Louis. Rapid desensitization Rapid desensitization, also called acute desensitization, is used to quickly and temporarily induce a state of tolerance to an allergen. This method is most often used for critically ill patients with an allergy to a life-saving medication which there are no feasible alternate agents, most commonly antibiotics, insulin, and chemotherapeutic agents. Small doses of the drug are introduced (either orally or intravenously, depending on the drug) and increased every 20–30 minutes until a therapeutic dose is reached. Patients who undergo acute desensitization commonly experience mild allergic side effects such as itching, hives, and wheezing. ==Mechanism of action==

SCIT Subcutaneous allergen immunotherapy involves subcutaneous injections of escalating doses of allergen over time. Allergen immunotherapy improves allergic symptoms via an early and late effects on the immune system. Early effects of allergen immunotherapy primarily involve suppression of mast cells and basophils, which increases the threshold of anaphylaxis. Later effects of allergen immunotherapy aim to induce or restore tolerance to the allergen by changing the antibody response from a largely IgE response to one predominated by an IgG subclass, mostly IgG4. Rapid desensitization The mechanism of action of acute desensitization is thought to be similar to that of the immune system's early response to SCIT. This procedure is thought to lead to subclinical activation of mast cells and basophils that have been sensitized with IgE against the drug, inducing them to gradually release their intracellular mediators at a rate that does not cause severe symptoms; eventually all of the cell-bound IgE is consumed by this process, leaving insufficient IgE available to cause an allergic reaction when subsequent therapeutic doses are administered. In order to maintain the desensitized state, the patient must have consistent therapeutic levels of the drug. If treatment is interrupted, then newly formed mast cells and basophils can be charged with newly secreted drug-specific IgE and can accumulate at levels sufficient to yield a new anaphylactic reaction. ==Protocol==

Reactivity is tested using oral food challenges or with skin prick tests. Phases 1 and 2 of sublingual immunotherapy are conducted in a supervised clinical setting. However, phase 3 can be done at home. ==History==

In the late 19th century and early 20th century, allergic conditions were increasingly attracting both medical attention (as an emerging public health problem) and scientific interest (aided by progress in biochemical techniques and the development of molecular and pathogenic theories). However, the many and varied treatment approaches were very unscientific. The British physicians Noon and Freeman were the first researchers to test pollen allergen immunotherapy in humans. Noon and Freeman, researchers at the Department of Therapeutic Inoculation at St. Mary's Hospital in London, published their findings in The Lancet in 1911. Building on the observations of his predecessors Bostock, Blackley and Dunbar, Noon noted that people with hay fever "sometimes become cured" and that this was possibly because they "have had the good fortune to develop an active immunity against the toxin." He hypothesized that by injecting people with hay fever with small amounts of a pollen "toxin", a state of immunity could be achieved. Allergen immunotherapy was part of mainstream medical practice for hay fever treatment in the 1930s. ==Society and culture==

Sublingual immunotherapy drops are currently commercialized and used in most European and South American countries, and in Australia and Asian countries. In most European countries, national regulations allow marketing of allergen products as "named patient preparations" (NPPs). In the United States, drop formulations have not yet received FDA approval, though off-label prescription is becoming common. In 2014, the FDA approved a once-daily sublingual tablet containing allergen extracts for the treatment of "hay fever" (allergic rhinitis with or without conjunctivitis). Recognition by international agencies The use of subcutaneous immunotherapy for treatment of environmental-based allergies and asthma is well supported by the majority of national and international allergy groups such as the World Allergy Organization, Canadian Society of Allergy and Immunology, European Academy of Allergy and Clinical Immunology, and the American Academy of Allergy, Asthma and Immunology. The use of sublingual immunotherapy is supported by few allergy agencies in order to allow for more investigation to occur on its practical use. The FDA currently allows individual allergists to create the formula for each dosage, whereas the EMEA requires treatment extracts to be prepared at manufacturing sites. Communication about allergen immunotherapy is not described very often in the news media; it is usually only communicated by the science community. The scientific community describes allergen immunotherapy as a scientific solution that helps not only patients with allergies but also positively impacts the quality of life of them and others around them. As temperatures increase due to changing climates, pollen levels also increase. Allergies are becoming a more common problem among the public, which is why the science community advocates for allergen immunotherapy. Subcutaneous allergen immunotherapy, according to the scientific community, is an effective solution to allergies due to numerous positive studies. ==Research==

Oral immunotherapy , oral immunotherapy's balance of risk to benefit for food allergies was not well studied. == References ==