Antibody response to Burkholderia cepacia in patients with cystic fibrosis colonized with Burkholderia cepacia and Pseudomonas aeruginosa

INTRODUCTION: This study was designed to determine the relationship between formation of serum antibodies to lipopolysaccharide (LPS) core antigen of Burkholderia cepacia and pulmonary colonization with B. cepacia and Pseudomonas aeruginosa in patients with cystic fibrosis (CF), and to define if an enhanced host humoral immune response to B. cepacia was related to a poor clinical outcome. METHODS: Serum IgG to B. cepacia LPS core antigen was measured in adult cystic fibrosis patients colonized with B. cepacia and P. aeruginosa, and serial titres were measured in 13 B. cepacia and 41 P. aeruginosa colonized patients followed prospectively over 18 months. RESULTS: The median B. cepacia antibody titre was significantly greater in the patients colonized with B. cepacia compared to those colonized with P. aeruginosa, a group which grew B. cepacia intermittently from their sputum. and nine healthy controls. The median antibody titre at recruitment into the study was significantly greater in patients who later went into exacerbations compared with those who remained clinically stable. but there was no difference between B. cepacia antibody titres in patients who died and those who survived the study duration. DISCUSSION: The degree of overlap of serum IgG levels to B. cepacia LPS core antigen in cystic fibrosis patients colonized with B. cepacia and P. aeruginosa does not allow this antibody to be used in a clinical context to define infection status. The magnitude of the humoral response to B. cepacia may influence occurrence of pulmonary exacerbations, but a more exuberant humoral immune response to B. cepacia core LPS is not the mechanism by which pulmonary deterioration occurs.