Researchers at Trinity College Dublin have published a groundbreaking study in the journal Allergy, identifying a link between rare immune cell types and treatment responses in chronic spontaneous urticaria (CSU), a condition characterized by recurrent hives.
Led by Professor Niall Conlon of the School of Medicine and Consultant Immunologist at St. James’s Hospital, the study is the first to demonstrate a connection between these rare cells and treatment outcomes. CSU, a common yet often underreported condition, causes individuals to experience unpredictable, intensely itchy hives and skin swellings without any apparent trigger. The UCARE center at St. James’s Hospital, which manages CSU, sees 10-20 new patients weekly. Unlike food allergies, CSU is not triggered by food or medicines.
Due to a lack of awareness, diagnosing CSU is challenging and often delayed. The condition can significantly impact individuals, causing distress, sleep disturbances, low mood, and anxiety, which affect work and personal relationships.
The study focused on a rare form of mast cells called myeloid progenitors in the blood of CSU patients. Researchers compared these cells in CSU patients and healthy controls and assessed responses to the anti-IgE therapy omalizumab. They found that patients with higher numbers of myeloid progenitors responded more quickly to omalizumab, suggesting these cells could predict treatment efficacy.
Dr. Barry Moran from Trinity Biomedical Science Institute (TBSI) highlighted the development of a flow assay to identify these rare cells, noting that the findings were supported by transcriptomic data.
David McMahon from the Irish Skin Foundation emphasized the profound impact CSU can have on quality of life, with symptoms persisting without a clear trigger for over six weeks. Misidentification as an allergic reaction is common, but avoiding suspected allergens does not alleviate the condition, leading to frustration.
While antihistamines can control symptoms for many CSU patients, high doses are often necessary. For those unresponsive to antihistamines, referral to specialist centers like the UCARE center at St. James’s Hospital is required. Here, patients may receive omalizumab, an anti-IgE biologic treatment.
Dr. Conor Finlay of the Trinity Translational Medicine Institute (TTMI) explained that activated mast cells release inflammatory factors causing itching and hives. Dr. Niall Conlon added that while omalizumab is effective for some, others experience slower or less effective responses. Understanding these variations could improve treatment strategies and patient outcomes.
Lead author Dr. Katie Ridge noted the challenges in studying mast cells, which are not found in the blood in their mature form. The team used a method to study immature mast cell progenitors, uncovering potential inflammatory signals in CSU and suggesting that the condition extends beyond the skin. Their findings may also have implications for other allergic diseases by enabling prediction of treatment responses through these rare cells.
