Diagnosis of systemic lupus erythematosus in Jamaica by Crithidia luciliae indirect immunofluorescence test

Abstract

The Crithidia luciliae indirect immunofluorescence test (CL-IFT) was compared with the DNA-binding assay for confirmation of the presence of double-stranded DNA (dsDNA) antibodies in cases of systemic lupus erythematosus (SLE). The study involved 142 patients whose sera had anti-nuclear antibodies (ANA). In 62 patients with clinical or suspected SLE, 66% gave positive CL-IFT results as against 69% by DNA-binding. Two patients who had negative CL-IFT results but positive DNA-binding were only marginally positive (31% and 36%). Anti-dsDNA antibody was not found in any ANA negative sera. C. luciliae is easily maintained in culture and the test is relatively easy to perform in any laboratory with facilities for doing fluorescence microscopy; we recommend it for confirmation of the diagnosis of SLE, especially in laboratories with limited resources.

The use of laboratory tests in the diagnosis of SLE

“…An assay should be accurate and produce the same result as other assays on all serum samples to enable comparison between diVerent centres. An international reference preparation (IRP) for anti- [33][34][35][36] CLIF is less likely than ELISA to detect low aYnity anti-dsDNA of uncertain clinical relevance, [37][38][39][40][41][42] especially if IgG specific conjugates are used. Local validation of each assay is essential to ensure adequate diagnostic performance.…”

“…Polyspecific ELISAs also detect low aYnity IgM antibodies of dubious clinical relevance and are less useful. ELISA results (particularly those detecting IgM) should be confirmed by IgG specific CLIF or Farr assays [33][34][35][36]. CLIF is less likely than ELISA to detect low aYnity anti-dsDNA of uncertain clinical relevance,[37][38][39][40][41][42] especially if IgG specific conjugates are used.…”

Autoantibody Determination in the Diagnosis of Systemic Lupus Erythematosus

“…ELISA detect both high‐ and low‐affinity IgM dsDNA antibodies and such ELISA results should be confirmed with CLIF or Farr assays. CLIF is less likely to detect low‐affinity anti‐dsDNA of uncertain clinical significance compared to ELISA [57–60].…”

Caracterização antigênica de moléculas de Leptomonas seymouri reativas com anticorpos anti Leishmania spp e anti T. cruzi

“…Os tripanosomatídeos do gênero Crithidia também se mostram de grande utilidade ao diagnóstico de doenças auto-imunes, como no lúpus eritematoso sistêmico (Aarden et al, 1975;Slater et al, 1976;Nilsson e Biberfeld, 1980;Fisher-Smikle et al, 1987). Pacientes com lúpus produzem anticorpos detectados pela reação de imunofluorescência indireta (IFI), que reagem com histonas e DNA complexado de C. luciliae (Aarden et al, 1975;Slater et al, 1976) (Wallace, 1966;McGhee e Cosgroove, 1980).…”

“…Especificamente para soros de pacientes com doenças auto-imunes era de se esperar alguma reatividade inespecífica, visto que, os tripanosomatídeos possuem cinetoplasto com DNA muito bem condensado, livre de proteínas associadas e por isso são utilizados, no caso da C. luciliae, como antígeno para a detecção de anticorpos anti núcleo (FAN) em indivíduos portadores por exemplo de Lúpus Eritematoso Sistêmico (Aarden et al, 1975;Fisher-Smikle et al, 1987;Nilsson e Biberfeld, 1980;Slater et al, 1976…”