Serum mucin-associated antigen levels of cystic fibrosis patients are related to their ages and clinical statuses.

Mucin levels are generally elevated in sera from many cystic fibrosis (CF) patients as measured by radioimmunoassay using monoclonal antibody 19-9, which is directed against the mucin-associated sialyl Lea antigen. Antibody 19-9 can only be used to measure mucin-associated antigen levels in those patients who are genetically able to make detectable levels of mucin-associated sialyl Lea epitope. Serial studies of 20 patients followed over 3-5 y showed that their serum mucin-associated antigen levels varied directly with respect to the severity of their disease and inversely with their Shwachman-Kulczycki clinical scores (p less than 0.001) and Brasfield chest roentgenographic scores (p less than 0.02). Serum mucin-associated antigen levels in samples from 89 CF patients were generally higher in the older patients (p less than 0.025). Serum mucin-associated antigen levels of CF patients who were colonized with Pseudomonas aeruginosa did not significantly differ from those of uninfected CF patients. The mean serum mucin-associated antigen level of CF patients colonized with Pseudomonas was higher than the mean mucin level of six non-CF bronchiectatic patients whose lungs were colonized with Pseudomonas (p = 0.053). Serum mucin-associated antigen levels are thus related to CF patients' ages and clinical statuses.