anti-neutrophil cytoplasmic antibody anti-neutrophil cytoplasmic antibody anti-neutrophil cytoplasmic antibodies (ancas) are a group of autoantibodies, mainly of the igg type, against antigens in the cytoplasm of neutrophils (the most common type of white blood cell) and monocytes. they are detected as a blood test in a number of autoimmune disorders, but are particularly associated with systemic vasculitis, so called anca-associated vasculitides (aav). perinuclear staining typical of p-anca the granular, cytoplasmic staining pattern of c-anca immunofluorescence staining pattern of anca. top left – pr3 antibodies on ethanol-fixed neutrophils (c-anca pattern). bottom left – pr3 antibodies on formalin-fixed neutrophils(c-anca pattern). top right – mpo antibodies on ethanol-fixed neutrophils (p-anca pattern). bottom right – mpo antibodies on formalin-fixed neutrophils (c-anca pattern).(fitc conjugate) anca if patterns