A serum test for cystic fibrosis using monoclonal antibody 19-9

Monoclonal antibody 19-9 detects a sialosylated Lea antigen with the following sugar sequence: NeuNAc alpha 2-3Gal beta 1-3[Fuc alpha 1-4]GlcNAc beta 1-3Gal. . . . This antigen is detected as a mucin in the sera of many patients with gastrointestinal and pancreatic cancer. Elevated levels of sialosylated Lea antigen are also detected in serum from 14 of 16 patients with cystic fibrosis (87%). One of the two negative patients belongs to the Le(a-b-) blood group and so is unable to synthesize the sialosylated Lea antigen. The high percentage of cystic fibrosis patients with elevated sialosylated Lea antigen suggests that the 19-9 antibody may be useful for diagnosis of cystic fibrosis. Antibodies to other sialosylated carbohydrates in mucins may also be useful for detection of cystic fibrosis and may allow diagnosis of patients belonging to the Le(a-b-) blood group.