P-ANCA

{{Short description|Type of autoantibody}} {{lowercase title}} thumb|Perinuclear staining typical of p-ANCA '''p-ANCA''', or '''MPO-ANCA''', or '''perinuclear anti-neutrophil cytoplasmic antibodies''', are antibodies that stain the material around the nucleus of a neutrophil. They are a special class of anti-neutrophil cytoplasmic antibodies.

This pattern occurs because the vast majority of the antigens targeted by ANCAs are highly cationic (positively charged) at pH 7.00. During ethanol (pH ~7.0 in water) fixation, antigens which are more cationic migrate and localize around the nucleus, attracted by its negatively charged DNA content. Antibody staining therefore results in fluorescence of the region around the nucleus.

==Targets== p-ANCAs stain the perinuclear region by binding to specific targets. By far the most common p-ANCA target is myeloperoxidase (MPO), a neutrophil granule protein whose primary role in normal metabolic processes is generation of oxygen radicals.{{cn|date=February 2024}}

ANCA will less commonly form against alternative antigens that may also result in a p-ANCA pattern. These include lactoferrin, elastase, and cathepsin G.{{cn|date=February 2024}}

When the condition is a vasculitis, the target is usually MPO.<ref name="FauciLangford2006">{{cite book|author1=Anthony S. Fauci|author2=Carol A. Langford|title=Harrison's rheumatology|url=https://books.google.com/books?id=9L2-H8lV1U0C&pg=PA159|access-date=1 November 2010|date=16 March 2006|publisher=McGraw-Hill Professional|isbn=978-0-07-145743-9|pages=159–}}</ref> However, the proportion of p-ANCA sera with anti-MPO antibodies has been reported to be as low as 12%.<ref name="ShoenfeldGershwin2007">{{cite book|author1=Yehuda Shoenfeld|author2=M. Eric Gershwin|author3=Pier-Luigi Meroni|title=Autoantibodies|url=https://books.google.com/books?id=TfW5sUfeM5gC&pg=PA98|access-date=1 November 2010|year=2007|publisher=Elsevier|isbn=978-0-444-52763-9|pages=98–}}</ref>

==Medical conditions== p-ANCA is associated with several medical conditions:<ref name="Lee2009">{{cite book|author=Mary Lee|title=Basic Skills in Interpreting Laboratory Data|url=https://books.google.com/books?id=AUSIRcV_as0C&pg=PA455|access-date=15 November 2010|date=10 March 2009|publisher=ASHP|isbn=978-1-58528-180-0|pages=455–}}</ref> * It is fairly specific, but not sensitive for ulcerative colitis, so is not useful as a sole diagnostic test.<ref name=Shepherd>{{cite journal |vauthors=Shepherd B, etal |year= 2005|title= Inflammatory Bowel Disease: Diagnostic and Treatment Options|journal= Hospital Physician|pages=11–19}}</ref> When measured together with anti-saccharomyces cerevisiae antibodies (ASCA), p-ANCA has been estimated to have a specificity of 97% and a sensitivity of 48% in differentiating patients with ulcerative colitis from normal controls.<ref>[http://gut.bmj.com/content/60/Suppl_1/A222.2.abstract] {{Cite journal | last1 = Walker | first1 = D. G. | last2 = Bancil | first2 = A. S. | last3 = Williams | first3 = H. R. | last4 = Bunn | first4 = C. | last5 = Orchard | first5 = T. R. | title = How helpful are serological markers in differentiating crohn's disease from ulcerative colitis in indian asian inflammatory bowel disease patients? | doi = 10.1136/gut.2011.239301.469 | journal = Gut | volume = 60 | pages = A222–A223 | year = 2011 | doi-access = free }}</ref> * Approximately 50% of cases of eosinophilic granulomatosis with polyangiitis * A majority of primary sclerosing cholangitis * Microscopic polyangiitis<ref name="HabermannClinic2007">{{cite book|author1=Thomas M. Habermann|author2=Mayo Clinic|title=Mayo Clinic Internal Medicine Concise Textbook|url=https://books.google.com/books?id=YJtodBwNxokC&pg=PA775|access-date=15 November 2010|date=1 November 2007|publisher=CRC Press|isbn=978-1-4200-6749-1|pages=775–}}</ref> * Focal necrotizing and crescentic glomerulonephritis * Rheumatoid arthritis

==References== {{reflist}}

Category:Autoantibodies