Presence of a serum hemagglutinin (lectinlike factor) in cystic fibrosis homozygotes and heterozygotes.

A lectinlike activity was discovered in serum from 25 patients with CF, 70 obligate heterozygotes (parents), and 18 of 27 siblings (67%) of 675 controls, 4.2% were found to have a positive test for the CF-lectin, approximating the 5% estimated prevalence of CF heterozygotes. The CF-lectin can be detected by dextran-enhanced agglutination of mouse RBCs and confirmed by agglutination inhibition with D-fructose. This simple and inexpensive assay has been found useful to detect carriers of the CF gene, but variability of commercial dextran and some unusual characteristics of the lectin itself have interfered with the successful completion of blind studies. All sugar moieties present in mucus inhibit the agglutination of mouse RBCs by CF serum, implying that the CF-lectin can bind the glycoproteins of mucus. The factor may play a role in the pathogenesis of Cf by stimulating mucus secretion and reacting with mucous glycoproteins to cause their precipitation. Most antibiotics remove or inhibit the CF-lectin activity, suggesting a therapeutic effect of antibiotics unrelated to their antibacterial action. This discovery of a lectinlike factor in the blood of patients with CF and their parents opens a new area for investigation of this devastating disease.