Antineutrophil cytoplasmic antibodies in Chinese patients with tuberculosis

Based on reports, infection with Mycobacterium tuberculosis is believed to induce the development of antibodies that are considered to be biological indicators for the diagnosis of some other diseases. However, conflicting results have been published regarding the presence of antineutrophil cytoplasmic antibodies (ANCAs) in patients with tuberculosis. We aim to study the seroprevalence of ANCA in a population of Chinese patients with tuberculosis, which may lead to the misdiagnosis of vasculitic disorders.

The study was conducted from January 2016 to May 2017 to evaluate the presence of ANCA in 103 Chinese patients using indirect immunofluorescent assay. An enzyme-linked immunosorbent assay was performed for anti-myeloperoxidase (MPO) and anti-proteinase 3 (PR3) detection.

Perinuclear ANCA (p-ANCA) was detected in 4.8% (5/103) of patients, whereas cytoplasmic ANCA (c-ANCA) was not detected; 1.9% (2/103) of patients with tuberculosis was positive for anti-MPO antibodies, and none had anti-PR3 antibodies. Both anti-MPO-positive patients were diagnosed with ANCA-associated vasculitides.

ANCA positivity may be more related to vasculitis and immunological disorders than to a M. tuberculosis infection. Therefore, to improve diagnostic accuracy, patients with M. tuberculosis who are ANCA positive should be investigated for concurrent diseases, including the effects of drugs. Therefore, even in tuberculosis epidemic area, ANCA seropositivity, detected by ELISA, is still more suggestive of ANCA-associated vasculitides.