Serum immunoglobulins and immunoglobulin G subclasses in cystic fibrosis related to the clinical state of the patient.

Levels of serum immunoglobulins and immunoglobulin G subclasses were measured in 32 cystic fibrosis (CF) patients, 30 asthmatics and 27 controls. When compared with the asthmatic patients and controls, the CF patients had raised levels of all IgG subclasses as well as total IgG, IgM and IgA, but there was not a statistically significant increase in IgE. The levels of immunoglobulins in the CF patients were examined in relation to the clinical features of the disease. Raised levels of IgG4 were related to levels of IgE, but these raised levels of IgG4 appeared to be part of a general increase in total IgG and not an isolated feature. There was a significant correlation between the total IgG level and its subclasses, IgG1, IgG2, IgG3, IgG4 and IgA. IgG1 was significantly correlated with IgG2 and IgG4; IgG2 with IgG4; and IgG4 with IgE. Total IgG was the immunoglobulin most closely correlated with poor lung function. Serum IgA was higher in patients with positive immediate skin prick reactions to pollens (p less than 0.005) and death within two years of the study was related to high levels of total IgG (p less than 0.01), IgG3 (p less than 0.001), IgA (p less than 0.001), and IgE (p less than 0.005).