Cystic fibrosis is a genetically conditioned disease, where a defective ion channel in the airway epithelium gives rise to mucus. The viscous mucus gets colonized by bacteria. In a young child staphylococci and other Gram-positive bacteria are predominating, but in older patients Pseudomonas aeruginosa becomes the dominating pathogen. The prognosis of cystic fibrosis varies. Some patients lose lung function early on, whereas others remain relatively unaffected high up into adulthood despite chronic bacterial colonization. Colonization with Paeruginosa is usually established by cultivation but may be detected earlier by means of serology (antibodies against the bacteria). The level of antibodies correlates with the quantity of bacteria in the airways.
Indications: Control of disease activity or assessment of prognosis of cystic fibrosis.
For reasons unknown many patients have autoantibodies against BPI, i.e. BPIANCA. IgG-BPI-ANCA is most common and may occur in up to 90% of the patients. About 40% have IgA-BPI-ANCA. There is a strong correlation between BPI-ANCA and colonization with Paeruginosa. Within the group of patients who are colonized by Paeruginosa a high level of BPI-ANCA is associated with a serious lung damage. It has been shown that positive IgA-BPI-ANCA is a risk factor for developing respiratory insufficiency within 5 years. IgA-BPI-ANCA has a stronger correlation to lung function impairment and Paeruginosa colonization than IgG-BPI-ANCA.