Some aspects of immunity in patients with cystic fibrosis.

Various aspects of the immune status were examined in patients with cystic fibrosis (CF) and the following observations were made. (1) Ten per cent of the CF patients had elevated or reduced serum IgG concentrations and there seems to be a transient low serum IgA concentration in the same number. Serum IgM concentrations were normal in CF patients. Normal levels of the three serum immunoglobulins (IgG, IgA and IgM) were detected in the siblings and heterozygotes. (2) Serum IgE concentrations were elevated in 32% of patients with CF but normal concentrations were detected in heterozygotes and siblings. (3) Precipitating antibodies to various antigens and allergens were detected in the sputum of most patients with CF, but their sera contained lower or undetectable titres of these antibodies. (4) The precipitating antibodies in CF sputum to bacteria, to agar, to seminal fluid, to urine and to human serum may be related to a common antigenic determinant of the glycoproteins present in all these fluids. (5) The total protein concentration in the sputum of CF patients seemed to reflect the extent of lung damage. (6) The third component (C) of serum complement concentration was normal, or moderately elevated in all CF patients tested. (7) Serum transferrin concentrations were normal in CF patients but their prealbumin levels were depressed, suggesting marginal undernutrition. (8) Peripheral blood lymphocyte transformations with PHA and PWM appear to be normal in CF patients. (9) Precipitins to the food antigens and the high percentage of positive sera with reticulin antibodies may be the result of malabsorption from the gut as well as a defect of the SIgA system. (10) The presence of free J-chain in the sputum of patients with CF may be further evidence of SIgA structural abnormality.