Serum eosinophil cationic protein and CD23 in acute RSV bronchiolitis

Elevated concentrations of eosinophil cationic protein (ECP) have been found in acute viral wheezing during infancy. Furthermore, RSV infection has been suggested to stimulate type-2 cytokine responses. The aim of this study was to test whether serum ECP and soluble CD23 levels, which are markers of eosinophil and IgE responses, respectively, are elevated in infants hospitalized for acute respiratory syncytial virus (RSV) bronchiolitis.

Fifty-five infants aged 1-12 months (median: 4.2 months) consecutively hospitalized for acute bronchiolitis were divided into two groups: RSV-positive (n=26) and RSV-negative patients (n=29). Serum ECP (s-ECP), soluble CD23 (sCD23), and total IgE were measured in all patients and in 23 asymptomatic infants (controls).

Lower s-ECP levels were detected in the RSV-positive group (5.4+/-4.3 ng/dl) compared with controls (9.38+/-5.95 ng/dl, p=0.02), but they did not differ significantly from the values of RSV-negative patients (7.8+/-5.7 ng/dl). There was a trend to higher s-ECP values in patients with a positive family history of atopy and/or a history of atopic dermatitis in the RSV-positive group (p=0.06). No differences in sCD23 and total IgE levels among the groups were detected. No correlation between total IgE and sCD23 values was observed.

There is no evidence from our data to suggest that either RSV-positive or RSV-negative acute bronchiolitis is associated with significant eosinophil-mediated degranulation. There is no evidence from the sCD23 data to support the hypothesis that IgE antibody responses are prominent during the acute illness.