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Thursday, June 9, 2016

Allergen Immunotherapy: No Evidence of Infectious Risk

Nearly three million Americans this year will be administered subcutaneous allergen immunotherapy for a variety of different reasons, including allergic rhinitis, asthma, allergic conjunctivitis, and venom allergy.  Altogether, these are over 16 million allergy shots.  Despite low risks of a large local reaction (0.7-4%) or systematic allergic reaction (0.2%), it has been shown to be relatively safe, cost-effective disease-modifying treatment.  However, recent proposed changes by the United States Pharmacopoeia requiring that vials of allergens be mixed in a strictly sterile fashion threaten the availability of allergen immunotherapy.

To investigate whether this is a real concern, Balekian and colleagues looked through the records of over 3000 patients who collectively received more than 130,000 injections over the preceding 10 years from Massachusetts General Hospital and Brigham and Women’s Hospital (J Allergy Clin Immunol 2016; 137(6): 1887-1888).  They could not find evidence of any local or systemic bacterial infection due to allergen immunotherapy.

Their research supports the community of allergists who maintain that current practices to guarantee sterility and safety are enough to prevent bacterial infection.  They conclude that the proposed changes won’t make a difference in infection rates, but will prevent people who need allergen immunotherapy from receiving them.

Identification of Immunoglobulin E

The year is 1966: Lyndon B. Johnson is the president squaring off against the Soviet Union, the Beatles are at the height of their popularity, and Neil Armstrong is training to one day become the first man on the moon.  And, tucked away in a laboratory at the Children’s Asthma Research Institute and Hospital in Denver, Colorado, Kimishige Ishizaka and his team are busy at work isolating the antibody that mediates allergic reactions, now called immunoglobulin E.

In this month’s issue of the Journal of Allergy and Clinical Immunology, Dr. Ishizaka recounts the way in which he and his team members eventually discovered reagin, later to be called Immunoglobulin E (J Allergy Clin Immunol 2016; 137(6): 1646-1650).  Through complex purification techniques and shrewd application of scientific principles on patients with plasma cell myeloma, he was able to identify the protein that led to a local reaction to ragweed, and figured out that the binding of allergens, like ragweed, dust mites and egg, to IgE on basophils and mast cells leads to histamine release.  Even though technology has advanced considerably and certain practices, like Dr. Ishizaka’s use of himself as a test subject, have changed, the role of Immunoglobulin E remains central to the field of allergy.

Omalizumab for the treatment of chronic spontaneous urticaria: a meta-analysis of randomized clinical trials

Imagine having an itch that you just couldn’t get rid of.  Worse yet, imagine that itch was accompanied by hives and localized swelling that can’t help but consume your attention.  That’s the reality for up to 1% of the world’s population, who have a disease called chronic spontaneous urticaria (CSU, also called chronic idiopathic urticaria).  The good news is that 70% resolve within 5 years. The bad news is that the standard treatment, non-sedating anti-histamines, only works in 50% of CSU patients.  That’s where Zhao and colleagues step in, with their article in this month’s issue of the Journal of Allergy and Clinical Immunology (J Allergy Clin Immunol 2016; 137(6): 1742-1750).

They examine the role of omalizumab, a medication that targets IgE, the human antibody which is central to the disease process of urticaria.  Omalizumab has been on the market for the treatment of urticaria since 2014.  Zhao and colleagues looked at 7 randomized controlled trials, with 1230 antihistamine- refractory CSU.  By metaanalysis, they assessed how effective and safe omalizumab is in the treatment of CSU. 

Their conclusion is that omalizumab has a safety profile comparable to placebo.  73% had an adverse effect with omalizumab, compared to 69% with placebo.  They also state that, at the dose of 300mg, omalizumab led to a complete response in 36% of patients.  Altogether, this suggests that omalizumab is a safe and effective treatment option for hard to treat chronic spontaneous urticaria.