Infants and young children with cystic fibrosis have high levels of serum sialyl Lewis(a) antigen.

Previous studies suggest that serum levels of the mucin-associated sialyl Lewis(a) (Le(a)) antigen (NeuAC alpha 2-3 Gal beta 1-3 [Fuc alpha 1-4]GlcNAc beta 1...) correlate with the pulmonary status of cystic fibrosis (CF) patients who have Le(a) or Lewis(b) blood types and can form the antigen. However, there is little information on serum sialyl Le(a) antigen levels in CF patients or normal children younger than 9 y. We measured serum antigen levels using the MAb 19-9 in normal term neonates, CF infants and young children, and infants and children who had bronchopulmonary dysplasia or asthma. The mean serum sialyl Le(a) antigen level of the CF patients was 46.7 U/mL, significantly above (p < 0.01) the mean levels of the three other groups. The mean serum sialyl Le(a) levels of the three non-CF groups were not significantly different from one another or from published normal values. We conclude that serum sialyl Le(a) antigen levels are elevated early in CF, but are normal in asthma and bronchopulmonary dysplasia patients.