{Reference Type}: Journal Article
{Title}: A dual-fixed neutrophil substrate improves interpretation of antineutrophil cytoplasmic antibodies by indirect immunofluorescence.
{Author}: Lin MW;Silvestrini RA;Culican S;Campbell D;Fulcher DA;
{Journal}: Am J Clin Pathol
{Volume}: 142
{Issue}: 3
{Year}: Sep 2014
{Factor}: 5.4
{DOI}: 10.1309/AJCPG02FGQVAUSIU
{Abstract}: <B>OBJECTIVE: </B>To determine whether the addition of a formalin-fixed neutrophil substrate could improve interpretation and prediction of autoantigenic specificity in antineutrophil cytoplasmic antibody (ANCA) testing.<BR><B>METHODS: </B>Routine diagnostic samples sent for ANCA testing were analyzed prospectively on a dual substrate of both ethanol- and formalin-fixed neutrophils. Positive samples on ethanol-fixed neutrophils were deemed "typical" if formalin-fixed neutrophils also stained, and "atypical" if not. Indirect immunofluorescence (IIF) results were correlated with antimyeloperoxidase (MPO) and anti-proteinase 3 (PR3) results with an enzyme-linked immunosorbent assay (ELISA).<BR><B>RESULTS: </B>Of 1,426 samples, 201 from unique patients were ANCA-positive (200 on IIF, 1 on ELISA alone). Thirty-two (45%) of 71 typical ANCA staining patterns were positive for either an anti-MPO or anti-PR3 antibodies, whereas only one (0.8%) of 129 atypical patterns was ELISA-positive, in a patient without systemic vasculitis. Only one (3%) of 34 ELISA-positive samples had a negative IIF-ANCA (1/1,426 patients, 0.07%), and this patient did not have vasculitis.<BR><B>CONCLUSIONS: </B>Concomitant staining on formalin fixation of IIF-positive ethanol-fixed ANCA samples improves the interpretation of ANCA testing and is predictive of vasculitis autoantigens MPO and PR3.