SUMMARYRecent reports suggest that DNA methylation is involved in the cause of autoimmune disease. We investigated the alteration of DNA methylation levels in lupus strains of mice, MRUlpr as a model, which develop an age-dependent lymphadenopathy and autoimmune disease. DNA methylation levels of thymus and axillary lymph nodes in 20-week-old MRWlpr mice, which are in an autoimmune disease state, were lower than those of 4-week-old MRUlpr mice with no symptoms as yet. No significant changes were observed in MRL/+ strain mice, which seemed normal at least 20 weeks, while DNA methylation levels in the spleen of both strains of mice increased significantly from the age of 4 to 20 weeks. However, no significant changes of DNA methylation levels in peripheral blood were observed with ageing in MRL strains. Moreover, we clarified that administration of 5-azacytidine had a strong effect on longer survival of MRLJlpr mice and reduced DNA methylation levels in the axillary lymph nodes and spleen. The possible relevance of DNA methylation levels to the progression of autoimmune disease is discussed.

No abstract

No abstract

A monoclonal antibody specific for a modified nucleoside, 5-methyl-2'-deoxycytidine (m5dCyd), was prepared using 5-methylcytidine (m5Cyd)-keyhole limpet haemocyanin (KLH) conjugate, and was characterized. Termed FMC9, the antibody reacts with m5dCyd and slightly with m5Cyd and 5-methylcytosine (m5Cyt) but not with other nucleosides tested in this investigation. FMC-9 was used in an enzyme-linked immunosorbent assay (ELISA) system for the quantitation of m5dCyd levels. Sensitivity was in the picomole range. Methylation levels in peripheral blood cells of healthy donors were determined by inhibition ELISA. The percentage of m5dCyd in peripheral blood cells of 10 healthy donors was 5.08 +/- 0.50%. These results suggest that the inhibition ELISA using FMC9 is useful to monitor m5dCyd levels in the peripheral blood cells.

No abstract