What is the Difference Between c-ANCA and p-ANCA?

The main difference between c-ANCA (cytoplasmic ANCA) and p-ANCA (perinuclear ANCA) lies in the proteins they target and their appearance in immunofluorescence microscopy. Both c-ANCA and p-ANCA are autoantibodies involved in ANCA (antineutrophil cytoplasmic antibodies) vasculitis, which is an autoimmune disease.

c-ANCA primarily targets proteinase 3 (PR3) and is typically found in patients with Wegener's granulomatosis. In immunofluorescence microscopy, c-ANCA produces a diffuse cytoplasmic staining pattern on ethanol-fixed neutrophils.

p-ANCA, on the other hand, focuses on a protein called myeloperoxidase (MPO). In immunofluorescence microscopy, p-ANCA exhibits a perinuclear/nuclear staining pattern on ethanol-fixed neutrophils. p-ANCA is most commonly associated with microscopic polyangiitis (MPA), idiopathic necrotizing crescentic glomerulonephritis (iNCGN), and Churg-Strauss syndrome (CSS).

Although there is not absolute specificity, c-ANCA is preferentially associated with Wegener's granulomatosis, while p-ANCA is more commonly associated with microscopic polyangiitis, idiopathic necrotizing crescentic glomerulonephritis, and Churg-Strauss syndrome.

Comparative Table: c-ANCA vs p-ANCA

Here is a table comparing the differences between c-ANCA and p-ANCA:

c-ANCA and p-ANCA are both autoantibodies or antineutrophil cytoplasmic antibodies that target specific proteins in the cytoplasm of neutrophils. They are mainly of IgG type and can be detected by blood tests. The antigens targeted by c-ANCA and p-ANCA are different, with c-ANCA targeting proteinase 3 (PR3) and p-ANCA targeting myeloperoxidase (MPO) and bactericidal/permeability-increasing protein (BPI). The fluorescence patterns produced by these autoantibodies are also distinct, with c-ANCA showing a diffuse coarse granular, centrally accentuated cytoplasm pattern, while p-ANCA shows a perinuclear space pattern in the cytoplasm.