Changes in cell differentiation and proliferation lead to production of abzymes in EAE mice treated with DNA–Histone complexes

Experimental autoimmune encephalomyelitis (EAE)‐prone C57BL/6 mice are used as a model of human multiple sclerosis. We immunize mice with myelin oligodendrocyte glycoprotein (MOG), DNA–histone and DNA‐methylated bovine serum albumin (met‐BSA) complexes to reveal different characteristics of EAE development including bone marrow lymphocyte proliferation and differentiation profiles of hematopoietic stem cells. Immunization of C57BL/6 mice with MOG(35‐55) results in the acceleration of EAE development. Anti‐DNA antibodies are usually directed against DNA–histone complexes resulting from cell apoptosis. During the acute EAE phase (7‐20 days after immunization), catalytic antibodies efficiently hydrolysing myelin basic protein (MBP), MOG and DNA are produced with parallel suppression of antibodies hydrolysing histones. We could show that in contrast to MOG, immunization with histone‐DNA results in a reduction of proteinuria, a significant increase in anti‐DNA, anti‐MBP and anti‐MOG antibody titres, as well as an increase in their catalytic activities for antigen hydrolysis, but slightly changes the concentration of cytokines. Contrary to MOG, DNA–histone and DNA‐met‐BSA only stimulated the formation of anti‐DNA antibodies hydrolysing DNA with a long delay (15‐20 days after immunization). Our data indicate that for C57BL/6 mice immunization with DNA‐met‐BSA and DNA–histone complexes may have opposing effects compared to MOG. DNA–histone stimulates the appearance of histone‐hydrolysing abzymes in the acute EAE phase, while abzymes with DNase activity appear at significantly later time‐points. We conclude that MOG, DNA–histone and DNA‐met‐BSA have different effects on numerous bone marrow, cellular, immunological and biochemical parameters of immunized mice, but all antigens finally significantly stimulate the development of the EAE.