ANCA against bactericidal/permeability-increasing protein, azurocidin, calprotection and defensins in rheumatic and infectious diseases: Prevalence and clinical associations

Objective. To determine the prevalence and clinical associations of ANCA against the antibiotic proteins and peptides: Bactericidal/permeability-increasing protein (BPI), Azurocidin (AZ), Calprotectin (CP) and β-Defensin-1 and -2 (DF). Methods. Patients with ANCA-associated vasculitides (n = 99), other vasculitides and rheumatic connective tissue diseases (n = 303), HIV-infection (n = 66), other infectious diseases (n = 134) Crohn's disease (n = 12) and ulcerative colitis (n = 12) were tested for BPI-, AZ-, CP-, DF-, PR3-, and MPO-ANCA in indirect immunofluorescence technique (IFT) and ELISA. Results. In ANCA associated vasculitides BPI-ANCA were detected in 6% of patients. In HIV infection, BPI was the main target antigen of ANCA-IFT positive sera (74%). BPI-ANCA was associated with higher inflammatory activity. In Crohn's disease and ulcerative colitis BPI-ANCA was prominent (34% of patients). AZ-ANCA were found in 5% of patients. No ANCA were detected against defensin and calprotectin. Conclusion. BPI-ANCA is the main autoantibody in HIV and is associated with higher inflammatory activity. In inflammatory bowel diseases BPI-ANCA is predominant, AZ-ANCA are also present to a lesser extend. Both were not useful characterize clinical subgroups. No ANCA were detected against calprotectin or defensins.