Background: Antineutrophil cytoplasmic autoantibodies (ANCA) are serological markers of ANCA associated systemic vasculitides (AASV), which is one of the most common multisystem autoimmune diseases. Features of Chinese patients with AASV have not been fully investigated. Objective: To analyse the clinical and pathological characteristics of Chinese patients with AASV. Methods: 426 Chinese patients with AASV diagnosed in the past eight years were retrospectively studied and their clinical and pathological data were analysed. Results: Of the 426 patients, 87 (20.4%) were Wegener's granulomatosis, 337 (79.1%) were microscopic polyangiitis and two (0.5%) were Churg-Strauss syndrome. Only 201 of 426 (47.2%) patients were diagnosed within three months. Clinically, the patients had multisystem involvement. Altogether 371 of 426 (87.1%) had kidney involvement and 260 of 426 (61.0%) had lung involvement. The prevalences of renal involvement and fatigue were significantly higher in patients with MPO-ANCA than that in patients with PR3-ANCA; the prevalences of ophthalmic, nasal involvement, rash, and arthragia were significantly higher in patients with PR3-ANCA than those in patients with MPO-ANCA. The one and five year death rates were 13.1% and 22.4%, respectively. The percentage of patients progressing to end stage renal disease at one and five years was 15.9% and 27.1%, respectively. Conclusions: AASV is not a rare autoimmune disease in Chinese people. Kidney and lung were the most vulnerable organs. For patients with multiorgan damage, an ANCA test should be performed to make an early diagnosis and to start treatment in time.

Various autoantibodies have been identified in sera from patients with systemic lupus erythematosus (SLE) and autoantibodies against neutrophil have been reported. It was suggested that antineutrophil autoantibodies might be involved in the pathogenesis of neutrocytopenia; however, the role of autoantibodies against neutrophil precursors and their specific target autoantigen(s) remained further characterized. The objective was to investigate the target antigens and clinical associations of autoantibodies against neutrophils and neutrophil precursors in patients with SLE. Sera were collected from 92 patients with SLE and renal biopsy proven lupus nephritis. Cell lysates of peripheral neutrophils (as mature neutrophils) from a normal blood donor and white blood cells from a patient with blast crisis of chronic granulocytic leukemia (CGL) (as neutrophil precursors) were used as antigens in Western blot analysis to detect autoantibodies in sera from patients with SLE. The clinical significance of antineutrophil autoantibodies that recognized different antigens were further analysed. Using normal peripheral neutrophils as antigens, two bands could be blotted: 64 kD (33/92, 35.9%) and 50 kD (13/92, 14.1%). The prevalence of anti-64 kD autoantibody in patients with positive rheumatic factor was significantly higher than that in patients without (54.5 versus 18.8%, P < 0.05). Using CGL white cells as antigen, five bands could be blotted: 60 kD (34/92, 37.0%), 50 kD (32/92, 34.8%), 29 kD (27/92, 29.3%), 42 kD (19/92, 20.7%) and 18 kD (16/92, 17.4%). The prevalence of anti-60 kD autoantibody was significantly higher in patients with neutrocytopenia than that in patients without neutrocytopenia (100 versus 48.3%, P < 0.01). The prevalence of anti-29 kD autoantibody was significantly higher in patients with alopecia than that in patients without alopecia (45.8 versus 20.8%, P < 0.05). Furthermore, the prevalences of anti-60 kD, anti-50 kD and anti-42 kD autoantibodies were significantly higher in patients with anti-Ro autoantibody than those in patients without; the prevalences of anti-29 kD and anti-18 kD autoantibodies were significantly higher in patients with anti-Sm autoantibody than those in patients without. We conclude that there are heterogeneous autoantibodies against both neutrophils and their precursors in sera from patients with SLE. Different autoantibodies may have different clinical significance.