Changes in plasma TARC levels during Japanese cedar pollen season and relationships with symptom development

Japanese cedar pollinosis (JCPsis) is an immunoglobulin E-mediated type I allergy caused by exposure to Japanese cedar pollen (JCP). Blood thymus and activation-regulated chemokine (TARC) levels are well known as an objective parameter for disease severity for several allergic disorders. The present study aims to evaluate the relationship between TARC levels and disease symptoms during the pollen season.

Analysis was performed of results of symptom scores and blood parameters obtained from 42 JCPsis patients who participated in a probiotic (Bifidobacterium longum BB536) intake trial in the JCP season of 2005 (January to April), using a randomized, double-blind, placebo-controlled design.

Significant increases in plasma TARC levels were observed in subjects receiving placebo (p < 0.05 in February and p < 0.01 in March), but not in subjects receiving BB536. Increased plasma TARC levels were markedly greater in subjects who experienced severe symptoms and were thus excluded early from the intervention (placebo group: n = 8; BB536 group: n = 2). Significant differences were found in changes from baseline TARC levels in February and March between the subjects where treatment was terminated early and the remaining ones. Among the remaining subjects, significant positive correlations were found as regards changed values of TARC compared to baseline in March and April with symptom scores recorded in the pollen season.

Changed values of blood TARC in the pollen season may offer promising parameters for assessing disease severity and monitoring treatment.