Background Anti-nuclear antibodies (ANA) are a hallmark in the diagnosis of systemic autoimmune rheumatic diseases (SARD). Their occurrence in several diseases like systemic lupus erythematodes (SLE), systemic scleroderma, Sjögren’s syndrome, myositis or others are used in classification and diagnosis and seem to be of pathological importance like anti ds-DNA antibodies or antibodies against nucleosomes.
Objectives ANA also occur in healthy individuals with increasing incidence in elderly. In female blood donors aged between 20 and 50 years Fritzler et al. (1) reported increasing frequencies of ANA with years of age. The aim of the present study was to determine the frequency of ANA in patients older than 50 years who attended a hospital specialized in geriatric medicine.
Methods In 347 patients aged between 51 and 101 years (median 77 years) admitted to a hospital specialized in geriatric medicineANA were measured using indirect immunofluorescence (iIF) on HEp-2 cells. Sera showing positive fluorescence at the screening titer of 1:40 were subsequently diluted. Endpoint titer and fluorescence pattern were recorded. In addition 316 patients were screened with commercial available enzyme immunoassays (EliA CTD Screen, Phadia, Freiburg, Germany) for 14 ANA subsets with known clinical relevance. Diagnosis of all patients tested positive for ANA were found in computer stored patient files.
Results At a screening titer of 1:40 118 (34 %) of patients were tested positive for ANA. Frequency of ANA positivity at a titer of 1:40 does not increase with age (25, 37, 34, 31, 38 and 34 % in patients of age groups 51–59, 60–69, 70–79, 80–89, >90 years). In contrast at screening titers 1:80 and 1:160 positivity rate of ANA increased with age (0, 5, 9, 11, 13 % and 0, 1, 4, 7, 13 % resp.). ANA fine speckled pattern was most frequently seen (n=76), followed by homogenous pattern (n=20), mixed homogenous and fine speckled pattern (n=15), speckled (n=3), nucleolar (n=2) peripheral (n=1) and large speckled (n=1). If just sera with titer >1:100 are considered as positive, fine speckled pattern was most frequently seen (n=13) followed by mixed homogenous and fine speckled pattern (n=9), homogenous (n=7), speckled (n=1) and peripherial (n=1).
With CDT Screen EIA 28 (8.8 %) patients were ANA positive. Out of these 28 patients we found 7 with anti-SSA/Ro activity, 3 with borderline reactivity to U1nRNP, 18 without a specific reaction to ENA (SSA, SSB, RNP, Sm, Scl-70, Jo-1) or centromeres.
Out of 118 patients tested positive for ANA (titer >=1:40) with iIF only 9 persons (7.6 %) were diagnosed suffering from systemic autoimmune rheumatic disease (1 CREST syndrome, 8 rheumatoid arthritis).
Conclusions Frequency of usual clinical significant titers (>1:100) of ANA increased with age in patients from 51 to 101 years of age. In most cases (92 %) these ANA were not associated with a systemic autoimmune disease. Increasing numbers of ANA positive elderly persons seems to be a side effect of aging rather than a sign of an active autoimmune disease.
Fritzler, M.J., Pauls, J.D., Kinsella, T.D. & Bowen, T.J. Antinuclear, anticytoplasmic, and anti-Sjogren’s syndrome antigen A (SS-A/Ro) antibodies in female blood donors. Clin Immunol Immunopathol 1985;36:120-8.
Klotz, W., Halder, W., Herold, M. (2012). Antinuclear antibodies in elderly people. Clin Chem Lab Med 2012;50: A277-278;P50.
Disclosure of Interest None Declared