Antineutrophil cytoplasm autoantibodies in patients with tuberculosis are directed against bactericidal/permeability increasing protein and are detected after treatment initiation.

OBJECTIVES To determine the prevalence of antineutrophil cytoplasm autoantibodies (ANCA) and its antigenic specificities in sera of patients with pulmonary tuberculosis (Tb) before and after treatment. PATIENTS AND METHODS Sixty-eight patients with culture-proven Tb were studied for the presence of ANCA, both by indirect immunofluorescence (IIF) and ELISA against proteinase-3 (PR3), myeloperoxidase (MPO) and bactericidal/permeability increasing protein (BPI). They were sought before treatment and in 52 of them also after therapy for the infection. High sensitivity C-reactive protein (CRP) was also measured at both times. RESULTS ANCA by IIF were found in 3/68 (4.4%) sera prior to treatment, one C-ANCA and two P-ANCA, all recognizing BPI. After treatment, this increased to 15/52 (28.8%), 3 C-ANCA and 12 P-ANCA, the majority directed against BPI (11/15, 73%). BPI-ANCA were positive in 6/68 (8.8%) and 15/52 (28.8%) before and after Tb after treatment initiation (p=0.003). PR3-ANCA and MPO-ANCA were negative in all Tb sera. A positive ANCA test correlated with CRP as inflammatory marker (p=0.001). CONCLUSIONS The prevalence of ANCA in culture positive Tb patients is modified by Tb chemotherapy. BPI is the main target antigen for ANCA in tuberculosis and BPI-ANCA increase after treatment.