The investigators recently showed an abnormal expansion of NK-like CD4+ T cells in Wegener's granulomatosis (WG), mainly in the diffuse vasculitis presentation. These cells expressed an assortment of activating NK cell receptors and their signaling partners, in particular DAP12. The investigators hypothesize that DAP12, or a downstream signaling target of DAP12, is the missing link between the different cell components involved in WG (neutrophils, macrophages, CD4 T cells).

The investigators will test our hypothesis of "DAP-12 gain-of-function" by quantitative (mRNA and protein) and qualitative (DNA, signaling and cellular activation) analysis of the DAP12 signaling pathway in WG patients with localized (group 1; n=30) or diffuse WG (group 2; n=30) by comparison with patients with micro polyangitis (group 3; n=30), or with sarcoidosis ( group 4; n=30), and healthy blood donors (group 5; n=30). Blood samples will be collected during a routine medical visit. These results may help to design future therapeutic strategies based on modulation of specific intra-cellular pathways involved in the disease.

Inclusion Criteria:

• Group 1: WG, with granulomatous lesions limited to upper airway or lungs and no evidence of generalized vasculitis ,± biopsy, ± anti-PR3 ANCA
• Group 2: WG with granulomatous lesions plus vasculitis expression (renal, neurological, skin, gut or heart involvement), ± biopsy, ± anti-PR3 ANCA
• Group 3: Necrotizing vasculitis with no granulomatous lesions, ± PAUCI immune glomerulonephritis, ± anti-MPO ANCA
• Group 4: clinical presentation compatible with sarcoidosis, ± biopsy, ± ECA elevated ± tuberculin anergy

Exclusion Criteria:

• <18 years
• Pregnancy or breastfeeding
• Absence of signed informed consent
• No affiliation to insurance