# The relationship between serum eosinophil peroxidase and major basic protein levels in relation to severity and response to H1 antihistamines in chronic spontaneous Urticaria

## TL;DR

This study finds that serum EPO and MBP levels are not reliable indicators of chronic urticaria severity or treatment response.

## Contribution

The study provides new evidence that EPO and MBP are not useful biomarkers for predicting CSU severity or antihistamine response.

## Key findings

- Serum EPO levels were higher in CSU patients compared to healthy controls but not correlated with disease severity.
- MBP levels did not differ between CSU patients and controls or correlate with disease activity.
- EPO and MBP levels decreased after antihistamine treatment but did not predict treatment response.

## Abstract

In chronic spontaneous urticaria (CSU), the significance of serum Eosinophil Peroxidase (EPO) and Major Basic Protein (MBP) levels as indicators of disease severity and response to antihistamine treatment is currently inadequately understood. This study explores the correlation between serum EPO and MBP levels, the severity of the disease, and the efficacy of antihistamines in patients with CSU.

A cross-sectional study involved 120 CSU patients alongside 30 healthy controls. In addition, a cohort study targeted 60 patients diagnosed with severe CSU, defined by a Urticaria Activity Score over 7 days (UAS7 ≥ 28). Initially, these patients received a dose of 20 mg of bilastine, which could be increased to a maximum of 80 mg depending on the results of the Urticaria Control Test (UCT) conducted on days 15, 30, and 60. Baseline serum concentrations of EPO and MBP were assessed for all participants, with follow-up measurements conducted after two months for those with severe CSU utilizing an ELISA kit..

Serum EPO concentration in the severe CSU group was similar to that in the non-severe group (P = 0.33) and was higher than that in the healthy control group (P < 0.001). Serum MBP concentrations did not differ among these three groups (P = 0.19). Serum EPO and MBP concentrations did not correlate with UAS7 and UCT. They did not differ among antihistamine response groups in the severe CSU group (P > 0.05) and decreased after 2 months of antihistamine treatment (P < 0.05).

Serum EPO and MBP levels are neither biomarkers predicting CSU severity nor factors predicting response to antihistamine in the severe group. This lack of association may help explain why treatments targeting eosinophil proliferation and chemotaxis have not been successful in clinical trials for patients with antihistamine-refractory CSU.