Peripheral blood analysis shows benefit of peptide immunotherapy for cat allergy
A pilot study has shown that an experimental vaccine for cat allergy can reduce the systemic immune response and symptoms of allergic rhinitis in individuals allergic to cats, including nasal congestion, sneezing, nasal itching and runny nose.
The vaccine, called Cat-PAD (Adiga Life Sciences Ltd.), uses peptide immunotherapy to train the immune system not to overreact to the cat allergen Fel d1 – a protein excreted in a cat’s skin, saliva, and urine.
Published in the journal Allergy, the study involved AllerGen and PROOF Centre of Excellence researchers from The University of British Columbia (UBC), McMaster University and Queen’s University. Dr. Scott Tebbutt (UBC) led the research. Dr. Young Woong Kim (UBC) is first author. Drs Mark Larché and Helen Neighbour (McMaster), and Dr. Anne Ellis (Queen’s) are co-authors and clinical leads.
“Our participants received four injections of the vaccine over three months and we measured their clinical response. We found that they had significant improvement in their nasal symptom scores and changes in the frequency of immune cells in their peripheral blood,” says Dr. Tebbutt.
Participants were individuals with cat allergy who had at least eight hours per week of exposure to a cat throughout the study. At each of three visits, they were exposed to cat allergen by a nasal allergen challenge (NAC) designed to provoke allergy symptoms.
After exposure, the researchers assessed participants’ total nasal symptom scores (TNSS) and collected peripheral blood to look for immunological changes and measure the neutrophil-to-lymphocyte ratio – a subclinical marker of inflammation that indicates an allergic response.
“We found a strong correlation between the change in the number of lymphocytes and the reduction of TNSS following immunotherapy treatment,” says Dr. Kim.
“Also, using a gene signature analysis, we identified five immune genes associated with this relationship that we look forward to studying further.”
The findings have clinical implications as well. In the current study and a 2018 paper, Drs Ellis and Neighbour validated the reliability of the NAC to induce AR symptoms, enabling future research of the potential efficacy of novel therapeutics.
Compared to existing immunotherapies, Cat-PAD requires fewer and less frequent injections and involves a significantly shorter course of therapy, according to Dr. Larché, who co-founded Adiga Life Sciences Inc.