A collection of reagents and other associated materials intended to be used for the qualitative and/or quantitative screening for multiple antibodies associated with vasculitis in a clinical specimen, using a multiplex method. The assayed antibodies may include autoimmune antibodies directed at the glomerular basement membrane (GBM), anti-neutrophil cytoplamic antibodies to myeloperoxidase (ANCA MPO) and/or anti-neutrophil cytoplamic antibodies to proteinase-3 (PR3).