Pneumology - Original Articles Open access

ABO blood group-dependent association of serum retinol-binding protein 4 with eosinophilic inflammation and spirometric parameters in adults with asthma

Authors

Published
16 October 2026
Issue
Early Access
Section
Pneumology - Original Articles

Abstract

Growing evidence links retinol binding protein-4 (RBP4) to inflammation; however, its association with inflammatory cell indices and spirometric parameters in asthma remains unclear, and the potential modifying role of ABO blood group has yet to be explored. The main aim was to assess the associations of serum RBP4 with inflammatory cell indices and spirometric parameters in adults with asthma stratified by blood group O and non-O.

Adults with physician-diagnosed asthma attending a respiratory clinic between January and June 2026 were consecutively enrolled in this cross-sectional study. Spearman's correlation assessed associations involving inflammatory cell indices, whereas Pearson's correlation evaluated associations between normally distributed serum RBP4 and spirometric parameters. Of the 88 adults with asthma enrolled, 64 had available ABO blood group data (38 O and 26 Non-O) and were included in the blood group-stratified analyses. In the O group, RBP4 was positively correlated with eosinophil count (ρ=0.35, p=0.03), eosinophil-to-neutrophil ratio (ρ=0.42, p<0.01), and eosinophil-to-lymphocyte ratio (ρ=0.41, p=0.01), whereas no significant associations were observed in the non-O group. Serum RBP4 was not correlated with spirometric parameters in either group. The forced expiratory volume in one second/forced vital capacity ratio was inversely correlated with eosinophil and lymphocyte counts only in the O group, while lymphocyte count showed an inverse correlation with forced expiratory flow between 25% and 75% of forced vital capacity in the non-O group. In conclusion, serum RBP4 was positively associated with eosinophilic inflammatory markers only in adults with asthma belonging to blood group O, whereas no such associations were observed in the non-O group.

Ethics Approval

This cross-sectional study was approved by Ethical Committee for Clinical Studies at the Faculty of Medicine, University of Kufa under approval number MEC-10; January 7, 2026.

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