A simple tablet could help people with grass pollen allergies.
Grass pollen allergy is the leading cause of seasonal asthma and hay fever globally with up to 30 per cent of the world's population allergic to grass pollen allergens.
In a discovery that may help scientists alleviate this global burden, Monash researchers have found that sublingual immunotherapy (SLIT) with a small tablet containing grass pollens, changed patient's immune memory cells in unexpected ways.
An allergy to grass pollens is more than a stuffed nose. It can mean time off from work or school, anxiety in parks and is the underlying cause of thunder-storm asthma.
According to lead researcher, Professor Menno van Zelm, from the Monash University Central Clinical School, recent studies from his lab have shown that sublingual immunotherapy (SLIT) against grass pollen allergy is known to protect against thunderstorm asthma and can protect against hay fever during the pollen season.
"Until now, we've had little understanding of how the immune system is stimulated by SLIT to provide protection against allergens," he said. "Understanding these processes is key to developing new treatments and for producing ways to test whether these new treatments are working, by finding biomarkers of immunity."
The study, published in the journal Allergy, recruited 27 patients allergic to ryegrass pollen and seasonal rhinoconjunctivitis, impacted by symptoms at least once a week.
Blood samples were taken from all participants outside of the allergy season, and then 13 received the sublingual therapy (in the form of one pill containing micro doses of pollen from five grass types dissolved under the tongue) for four months beginning in May/June before the allergy season while 14 received standard therapy such as antihistamines and/or intranasal corticosteroids.
The study was performed in 2019. It found that of the 13 in the clinical arm of the study – 92 per cent reported (12 of the 13) reported clinical benefits of the treatment two years later compared to the control group.
To understand why the positive results of SLIT remained for up to two years after a single dose, the researchers studied the immunological cell called the B cell which has the capacity to hold a "memory" of immunity against foreign invaders such as an allergen. They found that these memory B cells were reprogrammed and expressed new markers after 4 months of treatment.
Importantly, according to Professor van Zelm, these B memory cells can be used as biomarkers to test whether new treatments are working. "Because these cells – on response to treatment – stick around so long, and are specific for particular treatments, they are a very important way to monitor the success of new anti-allergy therapies," he said.
Allergen immunotherapy is a lengthy procedure, taking 3-5 years for sustained effects, so early markers of success are urgently needed to ensure that the right patients receive the optimal treatment as quickly as possible.
