Cytogenetic study and FISH analysis in lymphocytes of systemic lupus erythematosus (SLE) and systemic sclerosis (SS) patients

Systemic lupus erythematosus (SLE) and systemic sclerosis (SS) are autoimmune diseases characterized by the presence of antibodies against ubiquitous self antigens. The presence of clastogenic factors (CF) capable of inducing chromosome breakage has also been reported in the plasma of some patients. We aimed to assess basal frequency of cytogenetic damage in lymphocytes and presence of CF in the plasma of two groups of SLE and SS patients displaying a different antibody status (ACA-/Scl70+ or ACA+/Scl70-), using the micronucleus (MN) assay and FISH analysis with a pancentromeric DNA probe. As compared with controls, we found significantly higher MN frequencies in SS patients, but not in SLE patients. In addition, our data showed a significant prevalence of C-MN in SLE and ACA-/Scl70+ patients and of C + MN in ACA+/Scl70- patients. We observed a positive response in three out of the five CF experiments performed on plasma of SS patients. The three patients whose plasma caused MN induction were subtyped as ACA-/Scl70+, whereas the other subjects had ACAs. The same tests on six SLE patients gave negative results.