Antibody production deficiency with normal IgG levels in bronchiectasis of unknown etiology.

BACKGROUND: 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.

STUDY OBJECTIVES: To ascertain whether antibody production deficiency with normal total serum IgG levels is associated with bronchiectasis.

DESIGN: 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.

RESULTS: 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.

CONCLUSIONS: 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.