Plasma von Willebrand factor and endothelial-lineage flow-cytometry signals in acute pediatric IgA vasculitis: a...

Endothelial activation is implicated in childhood IgA vasculitis, but candidate endothelial markers may reflect systemic inflammation rather than endothelial perturbation.

In this single-centre cross-sectional pilot study, we enrolled 13 children with acute IgA vasculitis and 20 age- and sex-comparable healthy controls screened to exclude acute infection, allergic disease and other inflammatory conditions. Plasma soluble fms-like tyrosine kinase 1, soluble vascular endothelial cadherin, von Willebrand factor (vWF) and vascular endothelial growth factor were measured by enzyme-linked immunosorbent assay (ELISA); CD45-low CD31⁺CD146⁺ endothelial-lineage events were quantified by three-colour flow cytometry in a subset.

Children with IgA vasculitis had higher C-reactive protein, neutrophil proportion and platelet count than controls. In the pooled analysis, vWF was higher in patients than controls (median 811.1 vs. 439.9 ng/mL; Hodges-Lehmann difference 335 ng/mL, 95% confidence interval 133-539; P = 0.008; Benjamini-Hochberg q = 0.03), but this contrast did not persist after ELISA plate stratification (van Elteren P = 0.38) and is therefore hypothesis-generating. Within patients, no clear monotonic associations were detected between vWF and C-reactive protein or neutrophil indices; these exploratory analyses were underpowered to establish independence from systemic inflammation. No clear group differences were detected in the other soluble analytes. Endothelial-lineage events were nominally higher in patients, but this readout was strongly affected by CD45-low gate size and acquisition-session variability.

These findings support batch-controlled validation of vWF and more rigorous endothelial-cell enumeration in future pediatric IgA vasculitis studies.