Decreased interleukin-12 levels in umbilical cord blood in children who developed acute bronchiolitis

Respiratory syncytial virus (RSV) infection is common in young children, bu t only a few develop severe bronchiolitis. The relationship between bronchi olitis, asthma, and atopy has been debated for a long time, but the pathoge nesis of wheezing remains unclear. A Th1 and Th2-type lymphocyte imbalance seems to be involved in asthma and atopic disease. Serum interleukin-12 (IL -12), IL-10, and soluble CD30 (sCD30) levels were measured by enzyme-linked immunosorbent assay (ELISA) in 23 cord blood samples kept frozen since bir th: 11 from normal term newborns who several months later were admitted to the hospital with bronchiolitis, and 12 from newborns who did not develop t he disease (controls). The study was also performed on 28 additional childr en (1-16 months old) suffering an episode of acute bronchiolitis. IL-12 was clearly increased in all cases at birth, but newborns who later d eveloped bronchiolitis showed low IL-12 levels in cord blood compared to ne wborns who did not develop the disease (median 295 vs. 507 pg/mL; P = 0.001 ). sCD30 levels were also decreased in the first group (15 vs. 26 U/mL; P = 0.007). During episodes of bronchiolitis, a dear rise of IL-12, IL-10, and sCD30 was observed. None of the factors studied in the acute phase showed statistical differences in children who were later readmitted to the hospit al due to repeated wheezing crises. Children who develop acute bronchiolitis with wheezing may have an immunolo gical imbalance that is expressed at the time of delivery by a lower concen tration of serum IL-12. (C) 1999 Wiley-Liss, Inc.