Antibody Production Deficiency With Normal IgG Levels in Bronchiectasis of Unknown Etiology

No defined cause of bronchiectasis is currently found in approximately 50% of cases. Bronchiectasis is a common long-term complication in patients with primary hypogammaglobulinemia. To ascertain whether antibody production deficiency with normal total serum IgG levels is associated with bronchiectasis. Antibody response to a pneumococcal unconjugate vaccine and an Haemophilus influenzae type b conjugate vaccine was prospectively studied in all consecutive adult patients with bronchiectasis of unknown etiology who were assessed in our chest outpatient clinic from January 1994 to October 2001. Serum-specific antibodies were measured by enzyme-linked immunosorbent assay, and the results were compared with those obtained in a healthy adult control group. Antibody production deficiency was defined as a failure to respond to either vaccine. One hundred seven patients were included in the study (mean age, 46.3 years). Antibody production deficiency was diagnosed in 12 patients (11%). A significantly higher incidence of otitis media, lower serum IgG2 subclass levels, and lower preimmunization antibody levels to Streptococcus pneumoniae and H influenzae type b were observed in patients with antibody production deficiency. The probability of antibody production deficiency in patients with a history of otitis media was 20%, 26% in those with low IgG2 subclass levels, and 58% in those with both a history of otitis media and low IgG2 subclass levels. Antibody production deficiency with normal IgG levels may be associated with bronchiectasis, making it advisable to evaluate the antibody response to both the H influenzae and pneumococcal vaccines in patients with bronchiectasis of unknown etiology, particularly in those with a history of otitis media, low IgG2 subclass levels, and low levels of baseline specific antibodies.