The correlation of serum eosinophil cationic protein level with eosinophil count, and total IgE level in Korean adult allergic rhinitis patients.

BACKGROUND Eosinophil cationic protein (ECP) is present in eosinophil granules. It has been associated with eosinophil-associated disorders. OBJECTIVE We compared serum ECP levels in allergic and non-allergic rhinitis patients and evaluated the association with the eosinophil count and the total IgE level. METHOD We retrospectively reviewed medical records and categorized enrolled patients into the allergic (AR) and non-allergic rhinitis (NAR) groups. ECP, eosinophil count, and total IgE levels were reviewed in both groups. The association between ECP and the eosinophil count and total IgE level was further evaluated according to commonly detected specific antigens. RESULTS Six hundred and ten adults were included in the study. In the AR group (n=349), the median age was 27.0(23.0-42.0) years and the female:male ratio was 0.26:1. In the NAR group (n=261), the median age was 32.0(24.0-45.5) years and the female:male ratio was 0.33:1. We found that ECP (AR: 18.8(9.9-31.4), NAR: 14.8(8.2-24.9), p=0.003), eosinophil count (AR: 191.0(112.0-308.5), NAR: 149.0(91.0-249.0), p=0.002) and total IgE (AR: 166.0(58.4-422.5), NAR: 68.8(24.5-141.0), p<0.001) were higher in AR than in NAR patients. The ECP level was associated with the eosinophil count in both the AR (p<0.001) and NAR groups (p<0.001). A significant correlation between the ECP level and eosinophil count was demonstrated in AR patients who were skin test positive against house dust mite, animal and pollen allergens. CONCLUSIONS We suggest that ECP could be an important mediator in the pathogenesis of AR. The level of serum ECP was positively correlated with eosinophilia in AR patients regardless of the type of allergen sensitization. However, further study is warranted to verify the role of ECP in the clinical management of allergic rhinitis.