Properties of Uncommon Indirect Immunofluorescence Staining Patterns Determined during Antinuclear Antibody Detection on HEp-2 Cells

Abstract

In this study, we aimed to assess the prevalence of uncommon staining patterns found during testing for the presence of antinuclear antibodies (ANA) and to determine their association with certain antibodies and clinical diagnoses. Presence of ANA and the staining pattern was determined in 10955 samples using indirect immunofluorescence (IIF) on HEp-2 cells. ANA-positive samples were assessed for presence of 14 specific antibody types using a microbead based system. Demographic data (age, sex) and clinical diagnoses were collected from the referral documentation. Particular staining patterns were then compared with a representative comparison group comprised of samples with common staining patterns using these criteria. There were 22 patterns present in less than 3% of samples each and these were jointly present in 42.43% of ANA-positive samples. Specific antibodies were found in proportions similar to the comparison group (46.06%) and varied significantly between patterns. Likewise, there were significant differences in antibody distribution in particular patterns. Some patterns were associated with presence of rheumatic diseases or inflammatory arthropathies, while in others there was a concurrent diagnosis of liver disease, or a neoplastic process. Many of the uncommon IIF patterns have distinctive characteristics that warrant further investigation in order to determine their role in diagnosing various diseases, not limited only to the illnesses of the rheumatic spectrum. IIF on HEp-2 cells remains an irreplaceable method because of the diversity of ANA, only a number of which can be detected using other standardised methods.

Complex patterns on HEp-2 indirect immunofluorescence assay in a large sample referred for anti-cell autoantibodies detection

“…The simultaneous presence of other patterns was observed in more than 80% of the samples that depicted AC-6 and AC-7 patterns. Among the 22 ICAP patterns considered "rare", AC-6 and AC-7 were the patterns that most often appeared together with other patterns (38). In our study, AC-6,7 was the second most common single pattern found in association with another ICAP pattern.…”

Autoantibodies in COVID‐19, a possible role in the pathogenesis of the disease

“…The mechanism through which COVID‐19 would be able to induce specifically this kind of antibody is elusive and beyond the scope of this article, although there was mention of infections in earlier studies of this antibody [25]. For illustration purposes, we can compare their frequency in COVID patients with recent findings from a large study performed in the Croatian population [26], wherein this pattern was found in 41 (0.37%) of 10 955 analyzed samples referred for ANA‐testing ( p ‐value for the difference: <0.0001, χ 2 test). Its prediction of AKI deserves further investigations.…”