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Antinuclear antibody titration and pattern are helpful in the diagnosis of systemic autoimmune rheumatic diseases

Mohd Razi MS, Sugumaran Y, Mohd Haniz NA, Khilmie K, Osmera AH, Jauhary EJ, et al.

Malays J Pathol, 2024 Apr;46(1):63-69.
PMID: 38682845

INTRODUCTION: Anti-nuclear antibody (ANA) testing is among the most common immunological test requested in the diagnostic immunology laboratory. The main purpose of this test is to screen for the underlying systemic autoimmune rheumatic diseases (SARDs). The gold standard laboratory method for ANA detection is by the indirect immunofluorescence (IIF) assay. In most laboratories, positive ANA-IIF is reported in terms of titration and pattern.
OBJECTIVE: This study was conducted with the aim of determining the correlation between ANA-IIF titration and pattern for the diagnosis of SARDs.
MATERIALS AND METHODS: A retrospective study was conducted whereby the positive ANA-IIF samples from 1st July 2018 until 31st December 2019 and 1st January 2021 until 31st March 2021 were included in this study. The duplicate samples were excluded. ANA-IIF titration and pattern were recorded for all patients. The demographic, clinical, and final diagnosis data were retrieved from each patient's clinical note.
RESULTS: A total of 179 patients were included for analysis. The majority of the patients were female (79.9%) and from Malay ethnicity (66.5%). Sixty-five patients (36.3%) had ANA-IIF positive at 1:80 titration followed by 45 patients (25.1%) positive at titration of equal or more than 1:160. Speckled was the predominant pattern visualised in 90 patients (50.3%) followed by homogeneous in 76 patients (42.5%). Forty-five patients (25.1%) were finally diagnosed with SARDs with 41 of them diagnosed as SLE. ANA titration was significantly associated with the final diagnosis of SARDs at all titres (p<0.001) but the best cut-off was noted at a titre of equal or more than 1:320 with the sensitivity and specificity of 86.7% and 77.6% respectively. The homogeneous pattern was also significantly associated with SARDs (p=0.04). The final diagnosis of SARDs were significantly higher in female (p=0.03) and their age was significantly younger (p<0.001).
CONCLUSION: ANA-IIF titration of equal or more than 1:320 can be used as the best titration for differentiating between SARDs and non-SARDs in a positive ANA sample. Patients with homogeneous pattern were more likely to be diagnosed with SARDs than other ANA-IIF patterns.

Matched MeSH terms: Fluorescent Antibody Technique, Indirect/methods
Fulltext Serodiagnosis of melioidosis in Malaysia

Vadivelu J, Puthucheary SD, Gendeh GS, Parasakthi N

Singapore Med J, 1995 Jun;36(3):299-302.
PMID: 8553097

Current diagnosis of melioidosis is based on bacterial culture and/or serology which is becoming increasingly useful. An IgM-ELISA using heat-killed whole cells of Pseudomonas pseudomallei was developed and compared with an indirect haemagglutination technique (IHAT) and an indirect immunofluorescent technique(IFAT). The IgM-ELISA using a P:N ratio of > or = 2 had a sensitivity of 91% and a specificity of 96%. All 3 assays were further used in a seroepidemiological survey amongst different groups of patients and healthy individuals. It was found that the IFAT performed better than the IHAT, detecting antibodies to P. pseudomallei in 6% of diabetics, 5% of pyrexics, 8% of pregnant women and 3% of farmers. For the same groups the IgM-ELISA detected antibodies in 1% of pyrexics, 8% of pregnant women and a further 14% of farmers. The IgM-ELISA was found to be sensitive and useful for the serological diagnosis of acute melioidosis.

Matched MeSH terms: Fluorescent Antibody Technique, Indirect/methods*
Establishment of an immunofluorescence assay to detect IgM antibodies to Nipah virus using HeLa cells expressing recombinant nucleoprotein

Kaku Y, Park ES, Noguchi A, Inoue S, Lunt R, Malbas FF, et al.

J Virol Methods, 2019 07;269:83-87.
PMID: 30954461 DOI: 10.1016/j.jviromet.2019.03.009

A novel indirect fluorescent antibody test (IFAT) for detection of IgM against Nipah virus (NiV) was developed using HeLa 229 cells expressing recombinant NiV nucleocapsid protein (NiV-N). The NiV IFAT was evaluated using three panels of sera: a) experimentally produced sera from NiV-N-immunized/pre-immunized macaques, b) post-infection human sera associated with a Nipah disease outbreak in the Philippines in 2014, and c) human sera from a non-exposed Malaysian population. Immunized macaque sera showed a characteristic granular staining pattern of the NiV-N expressed antigen in HeLa 229 cells, which was readily distinguished from negative-binding results of the pre-immunized macaque sera. The IgM antibody titers in sequential serum samples (n = 7) obtained from three Nipah patients correlated well with previously published results using conventional IgM capture ELISA and SNT serology. The 90 human serum samples from unexposed persons were unreactive by IFAT. The IFAT utilizing NiV-N-expressing HeLa 229 cells to detect IgM antibody in an early stage of NiV infection is an effective approach, which could be utilized readily in local laboratories to complement other capabilities in NiV-affected countries.

Matched MeSH terms: Fluorescent Antibody Technique, Indirect/methods*
Detection of IgM antibodies against Legionella pneumophila serogroup 1 in Malaysian blood donors and patients with respiratory illnesses: evaluation of enzyme-linked immunosorbent assay and indirect immunofluorescence assay

Tay ST, Lakhbeer Singh HK, Ramasame SD, Vadivelu J

Jpn J Infect Dis, 2009 Sep;62(5):409-10.
PMID: 19762997
Matched MeSH terms: Fluorescent Antibody Technique, Indirect/methods*