Formalin fixation and patterns of antineutrophil cytoplasmic antibodies.

Abstract

Recent publications have suggested that fixing neutrophils in formalin is a useful adjunct to the differentiation of antinuclear antibodies from perinuclear antineutrophil cytoplasmic antibodies. In this small comparative study of 30 sera the use of an additional slide of formalin fixed neutrophils did not add any useful information and may be confusing as the results were not reproducible. (7 Clin Pathol 1995;48:89-90)

Specificities of anti-neutrophil autoantibodies in patients with rheumatoid arthritis (RA)

“…However, other groups have not found a similar degree of antinuclear reactivity using formaldehyde-fixed neutrophils, and have concluded that all antineutrophil autoantibodies represent ANCA [ 12,131. Possible reasons for this discrepancy may include methodological differences and the fact that formaldehyde fixation methods are not standardized and are of low reproducibility [26,27].…”

A Dual-Fixed Neutrophil Substrate Improves Interpretation of Antineutrophil Cytoplasmic Antibodies by Indirect Immunofluorescence

“…6,8,[11][12][13][18][19][20][21] Results have been highly variable, possibly because of differences in methodology, such as variable incubation times, concomitant use of acetone, different types of formalin (vapor vs liquid), and different types of alcohol fixative (ethanol vs methanol). Only five studies, performed in very selected patient populations, have specifically addressed the issue of PR3 and MPO specificity in relation to the use of formalin-fixed neutrophils, 8,11,16,20,21 and generated results consistent with those reported here in our otherwise unselected cohort.…”

“…[6][7][8][9][10] Despite initial enthusiasm for this approach, other studies have identified inconsistencies, including false positivity owing to enhanced autofluorescence on the formalin-fixed substrate. [11][12][13] Given these controversies, the selective nature of the cohorts examined in these studies and the paucity of reports correlating IIF-ANCA patterns on a dual substrate with autoantigenic specificity, we examined the latter approach to ANCA testing in the routine diagnostic laboratory.…”

How to test for antineutrophil cytoplasmic antibodies--evidence based immunology?

“…5 Unfortunately, at the time this technique had never been formally evaluated in the international workshops and there were no adequate data confirming the technique to be useful. There is no standardised method for the use of formalin fixed neutrophils, and our own previously published data 6 and more recent extended data presented at the last International ANCA Workshop in Birmingham confirm that this technique is not reproducible. Informal discussions with leading international figures in the field at this meeting confirmed that many had tried formalin fixation but had also found it to be unreliable, although it is regrettable that these "negative data" have not been placed in the public domain.…”