Expression of Ro/SS-A and La/SS-B determined by immunohistochemistry in healthy, inflamed and autoimmune diseased human tissues: a generalized phenomenon.

OBJECTIVE: Autoantibodies to the ribonucleoproteins Ro/SS-A and La/SS-B are found in autoimmune diseases such as primary Sjögren's syndrome (pSS), systemic lupus erythematousus and rheumatoid arthritis. Increased and aberrant expression of Ro/SS-A and La/SS-B in target organs, which have been reported in the recent literature, might contribute to their antigenicity. However, data on the expression of Ro/SS-A and La/SS-B in other inflammatory conditions are scarce. MATERIALS AND METHODS: Using monoclonal antibodies against Ro/SS-A and La/SS-B, we studied the expression of these antigens in paraffin-embedded healthy tissue, aspecific inflamed tissue, the neonatal and adult cardiac conduction systems and labial salivary gland tissues of patients suspected of having pSS. RESULTS: In healthy tissues, the nuclei expressed both Ro/SS-A and La/SS-B. This expression was stronger in inflamed tissues. Nucleoli were negative and cytoplasmic expression was weaker than nuclear expression. No increased or aberrant expression of Ro/SS-A or La/SS-B was observed in either neonatal or adult atrioventricular nodes and bundle branches. More pSS patients showed high La/SS-B immunoreactivity levels in their labial salivary gland ductal cell nuclei than non-Sjögren's syndrome sicca patients. CONCLUSIONS: Ro/SS-A and La/SS-B expression is a generalized cell biological phenomenon and may be upregulated by increased cell activation both in aspecific and autoimmune-mediated inflammation. In pSS the high expression of La/SS-B in labial salivary, gland ductal cell nuclei might contribute to the local immune response.

Time between onset of apoptosis and release of nucleosomes from apoptotic cells: putative implications for systemic lupus erythematosus.

OBJECTIVE: To investigate the kinetics of nucleosome leakage from apoptotic cells in an in vitro system and extrapolate the results to autoimmune disease, in particular systemic lupus erythematosus. METHODS: A sensitive nucleosome enzyme linked immunosorbent assay (ELISA) was developed, using a monoclonal antibody (mAb) against histone 3 and an mAb against nucleosomes. Nucleosome release during apoptotic cell death was studied in Jurkat cells. AnnexinV binding (early apoptosis) and propidium iodide positivity (late apoptosis) of the cells were compared with nucleosome release at different times after apoptosis induction. RESULTS: Nucleosomes appeared in culture supernatant of Jurkat cells 24 to 48 hours after apoptosis induction, when the cells had been late apoptotic for more than 12 hours. CONCLUSION: Nucleosomes are released from late apoptotic Jurkat cells, with a 12 hour delay from the appearance of AnnexinV binding cells. This result suggests that in vivo scavenger mechanisms have 12 hours to remove apoptotic material from the circulation.

Methodological update detection of antibodies to dsDNA: current insights into its relevance.

Ever since its first discovery in 1957, anti-DNA has taken a special place amongst the other antinuclear antibodies. Even today, it stands out between these, because of its high specificity for one particular disease: systemic lupus erythematosus (SLE). Furthermore, anti-DNA has been shown to actually play a role in a key disease feature of SLE: lupus nephritis. Binding of anti-DNA to the glomerular basement membrane of the kidney has been shown to be mediated by nucleosomes. More recently, it has been shown that patients with SLE also have antibodies specific for nucleosomes in their circulation. It may well be that anti-nucleosome detection in the near future will prove to be of more relevance than anti-DNA detection. Nucleosomes also seem to play a key role in the induction of anti-DNA (and anti-nucleosome) production. Mechanisms involved in this process may include defects in apoptosis and/or clearance of apoptotic material. Studies of these mechanisms will help us to decipher the cause of autoantibody production, or indeed of autoimmune diseases such as SLE.