Which antibodies to test for in the evaluation of vasculitis. When considering workup for an autoimmune and vasculitic etiology of an unexplained arterial thromboembolism, consider ordering erythrocyte sedimentation rate, C-reactive protein, ANA, rheumatoid factor, ANCA, and C3 and C4 complement. ANA, antinuclear antibodies; ANCA, antineutrophil cytoplasmic antibodies; ds-DNA, double-stranded DNA; MPO, myeloperoxidase; PR3, proteinase 3; RNP, ribonucleoprotein; SM, SM proteins (core proteins of small nuclear ribonucleoproteins).