ANTI-NUCLEOSOME ANTIBODIES - A NOVEL TEST IN SYSTEMIC LUPUS ERYTHEMATOSUS

In this study the serum levels of specific anti-nucleosome autoantibodies (autoAb) were measured in the follow up of the group of SLE patients and compared to the levels of anti-dsDNA, C3, C4 components of complement, to ECLAM- European Lupus Activity Measure and to the levels of sVCAM-1, sICAM-1, neopterin, sIL-2r, IL-10 and fas ligand. Anti-nucleosome antibodies were detected using an enzyme immunoassay for the quantitative determination of autoAb to nucleosomes and their components in the human serum in the group of 52 patients, 50 of them female, who all fulfilled criteria of SLE according to ACR (American Colledge of Rheumatology). Anti-nucleosome antibodies were followed up during 3 subsequent measurements during six months and compared to the development of ECLAM index, the levels of anti ds-DNA antibodies and C3, C4 complement components levels and other activity markers. The probands with the stable low disease activity had the lowest levels of anti-nucleosome Ab (83 ±33.0 IU/ml). The patients with the stable high or increasing activity had the mean titers in the first series 200.42 ±36 IU/ml and 192 ±65 IU/ml and 188±58.11 IU/ml in the 2. and 3. serial measurement. Subgroup with the high starting activity and with decrease of the activity index had the mean levels of 223 ±39.0IU/ml, 185.6 ±37.6 IU/ml and 207 ±55.5 IU/ml during three measurements. In the subgroup of patients with lupus nephritis (LN) n=15, the anti-nucleosome Ab levels were 176 ±34.0 IU/ml, 174 ±30.0 IU/ml and 148±32.0 IU/ml. A strong correlation was found between levels of anti-nucleosome and anti-dsDNA antibodies. All sera with anti-dsDNA antibodies over 40 had at the same time positive titer of anti-nucleosome antibodies, however, 21 sera with negative anti-dsDNA had positive test for antinucleosome antibodies. Anti-nucleosome antibodies correlated with ECLAM activity index and reversibly with C4. No correlation was established with levels of C3, sVCAM-1, sICAM-1, IL-10, fas ligand, neopterin and sIL2r. The examination of anti-nucleosome Ab contributes to the early diagnosis and is an instrument in the differential diagnosis of the connective tissue diseases and it seems to be especially valuable in anti-dsDNA negative lupus. The use of anti-nucleosome antibodies measurement as a marker of disease activity deserves further evaluation.