D1.496 - Variation in platelet-activating factor levels among patients with chronic spontaneous urticaria

Chronic spontaneous urticaria (CSU) is a heterogeneous, immune-mediated disease characterized by recurrent wheals and/or angioedema. Its pathophysiology involves complex interactions between mast cells, basophils, and multiple inflammatory mediators, yet reliable biomarkers for disease activity and clinical phenotypes remain limited. Platelet-activating factor (PAF) is a potent phospholipid mediator that promotes mast cell degranulation, increases vascular permeability, and activates leukocytes. Elevated PAF levels and reduced PAF-acetylhydrolase activity have been reported in CSU, particularly in patients with severe disease and angioedema.  

This study aimed to evaluate plasma PAF concentration in CSU patients, investigate differences across clinical subgroups, and examine associations with disease characteristics.

In this prospective study, 206 patients with CSU from Pauls Stradiņš Clinical University Hospital and the Center for the diagnosis and treatment of allergic diseases were included. Clinical data were collected, and PAF levels were measured in peripheral blood plasma using ELISA. Data analysis was performed using Jamovi version 2.3.28.

The study population had a mean age of 42 years, and 77.7% of participants were female. Median PAF was 16.3 ng/mL (IQR 12.6–18.5). PAF levels were significantly higher in patients with angioedema (with or without urticaria) compared to urticaria alone (17.2 ng/mL and 17.1 ng/mL vs. 14.1 ng/mL; p=0.002). Elevated PAF correlated positively with nocturnal symptoms (r=0.071, p=0.018), older age (r=0.141, p=0.007), later disease onset (r=0.145, p=0.006), and inflammatory/immune parameters including IgG-anti-IgE (r=0.142, p=0.006), HSP70 (r=0.120, p=0.030), total IgM (r=0.193, p=0.025), and CD4/CD8 index (r=0.193, p=0.001). PAF also correlated positively with parathyroid hormone (r=0.334, p=0.023) and serum amyloid A (r=0.535, p=0.046), and negatively with carcinoembryonic antigen (CEA) (r=0.220, p=0.026). No significant associations were observed with other clinical or laboratory parameters, nor with disease activity questionnaires.

Elevated plasma PAF levels in CSU patients correlate with multiple inflammatory markers, supporting its role as an indicator of systemic inflammation. Patients with angioedema and nocturnal symptoms—who typically experience a more severe disease course—exhibit higher PAF, suggesting that PAF may serve as a marker of disease severity and inflammation in CSU.