Opsonic Defect in Patients with Cystic Fibrosis of the Pancreas

Cystic fibrosis of the pancreas is one of the most common inborn errors of metabolism. The high incidence of morbidity and mortality in these patients is primarily due to severe and frequent pulmonary infection. To date, no immune deficiency has been found in cystic fibrosis patients. Their sera contain normal quantities of immunoglobulins and hemolytic complement. In an assay of phagocytosis by alveolar macrophage, six out of nine sera from cystic fibrosis patients failed to support normal phagocytosis of Pseudomonas aeruginosa. This deficiency could be corrected by increasing the concentration of serum used in the assay. By contrast, their sera supported normal phagocytosis of Pseudomonas by blood polymorphonuclear leukocytes and continued to support normal phagocytosis when serum dilutions were used. Two patients with severe isolated deficiences of serum immunoglobulin A were found to have a similar defect in the alveolar macrophage assay, but normal phagocytosis by polymorphonuclear leukocytes. It is postulated that cystic fibrosis patients may have a quantitative and (or) functional defect of IgA antibodies, specific for Pseudomonas, and possibly of importance in the pathogenesis of their pulmonary disease.