Immunoglobulin levels in bronchoalveolar lavage fluid of children with chronic chest disease.

The concentration and distribution of immunoglobulin isotypes (IgG, IgM, sIgA) and IgG-subclass levels (IgG-1-4) were measured in bronchoalveolar lavage fluid (BALF) in 47 children with chronic chest disease (age range 1.0-9.9 years) and 18 healthy controls (age range 1.0-6.25 years). Of these patients, 19 had nonallergic asthma (Group A), 19 suffered from recurrent pneumonia or chronic bronchitis (Group B), and 9 patients had IgG-2 deficiency (Group C). In all individuals, IgG was the predominant immunoglobulin in the lower respiratory tract, followed by IgA and IgM. In patients of Group A and B, IgG, IgM and IgA levels in BALF were significantly elevated when compared to controls. Assessment of IgG-subclass concentrations in BALF revealed that IgG-1 levels were increased in Group A and B when compared to controls (P < 0.05). Since this difference could not be explained by difference in age, it is possibly due to the inflammatory process at the mucosal level. IgG-2 levels were elevated in all patients except those with IgG-2 deficiency. IgG-2 concentration in the IgG-2 deficent group was lower compared to controls (P < 0.005) and patients in Group A (P < 0.0005) and B (P < 0.005). IgG-3 levels were elevated in asthmatics in group A compared to healthy controls (P < 0.005). IgG-4 concentrations were the same in all study groups. Since IgG-subclasses in percentage of total IgG were similar in BALF and serum, our results do not indicate a local production of any of the IgG-subclasses in the respiratory tract. Copyright 2000 Wiley-Liss, Inc.