Anti-neutrophil cytoplasm antibodies (ANCA) are defined as important serological markers for the diagnosis of some forms of small vessel vasculitis, including granulomatosis with polyangiitis (GPA) , microscopic polyangiitis(MPA) and to a lesser extent Churg -Strauss syndrome or Eosinophilic granulomatosis with polyangiitis (EGPA).So they are called ANCA-associated vasculitis(AAV).

An international consensus statement for ANCA testing statement was issued in 2017 and states that the antigen specific immunoassays can be used for the accurate diagnosis of ANCA-associated vasculitis without the need for indirect immunofluorescence(IIF). In the present study we will test whether the antigen specific assays screening is a valuable alternative to IIF confirming with immunoassay for the diagnosis of AAV on a number of patients and controls.

Aim To evaluate the performance of the recommended strategy for the detection of ANCA based on screening with antigen specific immunoassays on a number of AAV patients and relevant disease controls In Kagawa university hospital (rheumatology department).

Patients and methods This is a prospective study will be conducted at the department of rheumatology in Kagawa university hospital in which consecutive samples will be included from patients suspected to have AAV; patients subsequently identified as having AAV will be included as AAV patients, while patients in which the diagnosis AAV is rejected, will be included as disease controls. PR3-and MPO-ANCA will be performed using assays from Medical & Biological Laboratories Co (Anchor CLEIA) isayama.takuya@mbl.co.jp

To evaluate the performance of the recommended strategy for the detection of ANCA based on screening with antigen specific immunoassays on a number of AAV patients and relevant disease controls (i. e., patients for whom ANCA would be requested in the context of small-vessel vasculitis such as patients with infections, drug-induced diseases, connective tissue disease, etc.).

Inclusion Criteria:

.All patients included must be older than 18 years and able to give informed consent.

• Classification criteria and nomenclature for AAV are from the American College of Rheumatology
• Serum sampling should be done before initiation of immunosuppressive treatment or no later than 2 weeks after onset of low-medium dose of immunosuppressive treatment (but this should be documented)

Exclusion Criteria:

.Patients younger than 18 years old

primary care clinic