Adding a lab-made antibody to an allergy shot may build the immune system better against cat allergies than standard injections alone.Combination therapy also reduces allergy symptoms within a year of stopping treatment, new study finds
Allergy shots, also known as immunotherapy, have been used for more than a century to reduce itching, watery eyes, sneezing, runny nose, congestion and other allergy symptoms. Injections contain small amounts of things people are allergic to, called allergens. People get weekly or monthly injections for three to five years and gradually build up tolerance to the allergen.
Despite their long use, scientists don’t know exactly how allergy shots work, said Lisa Wheatley, an allergist at the National Institute of Allergy and Infectious Diseases. Some people’s allergies are largely curable, while others may require injections indefinitely. “We know that if you give a cat immunotherapy [allergies] …you’ll be better off after that year, but you won’t keep that benefit. “
The study was conducted to see if researchers could improve allergy treatment by reducing the time injections are needed, while still giving patients lasting relief. The team also wants to better understand how immunotherapy works, she said.
When an allergy strikes, some immune cells produce alarm chemicals that trigger inflammation and other symptoms. “If we can suppress ‘danger’ signals, we might be able to improve immunotherapy,” Wheatley said.
She and colleagues used a monoclonal antibody called tezepelumab to block one of the alarm chemicals, thymic stromal lymphopoietin (TSLP). The antibody is already used as an asthma treatment, so researchers already know it’s generally safe.
The researchers gave 121 feline allergy patients the standard allergy vaccine alone, tezepelumab alone, a combination of the two, or a placebo. On its own, tezepelumab was no better than a placebo, the researchers found.
After a year of treatment, people who get the combination Reduce allergy symptoms Researchers on October 9 at Journal of Allergy and Clinical Immunology.
And even one year after people on the combination stopped treatment, levels of an allergy-triggering antibody called IgE dropped and continued to drop. In people who received standard injections, once treatment was stopped, IgE levels began to rise back to baseline levels, Wheatley said.
One reason the therapy might work is that it alters the activity of genes in some immune cells that trigger inflammation, the team found. An analysis of nasal swabs showed that immune cells called mast cells produced less tryptase, one of the main chemicals released in allergic reactions, in people who received the combination therapy.
Edward Zoratti, an allergist and immunologist at Detroit’s Henry Ford Hospital, said that while the results are encouraging, it’s unclear whether tezepelumab will work for other allergies as well. “Are they lucky and chose the right allergen?”
Cat allergies are Fel d1 in cat saliva and dead skin cell sheets or dandruff (SN: February 13, 2020). In contrast, cockroach allergies can arise from a variety of proteins.
Another possible downside, Zoratti said, is that monoclonal antibodies are expensive.
More research is needed before this or any other therapy can be added to allergy shots in a doctor’s office, but this research is important for understanding how allergy therapy works, he said. “This is one step in a long chain that may lead us to a truly useful therapy in the future.”