Histones are a set of highly cationic proteins essentially involved in the binding and compaction of DNA in the cell nucleus chromatin (1-3). In mammals, five subclasses of histones exist: H1 (f1), H2a (f2a2), H2b (f2b), H3 (f3), and H4 (f2a1) (4,5), whereby four histones form an octameric core protein aggregate (H2a, H2b, H3, H4) around which a 145-bp DNA molecule is wrapped, forming the core particle followed by a variable (-55 bp) DNA region, complexed with H1 (6). In the cell nucleus, histones and DNA are present in similar quantities .These components of the cell nucleus are two of the most important antigens for autoantibody formation in SLE (7-12), and it has been reported that the titers of both groups of autoantibodies correlate well with disease activity (13-16).A prominent manifestation oforgan involvement in SLE patients is the occurrence of immune complex (IC)' glomerulonephritis . After the original report by Koffler et al. (17), attention has been focussed on the role of DNA-anti-DNA IC for >20 yr. Two proposals have been widely discussed in connection with the glomerular deposition of DNA-anti-DNA complexes: the now unfashionable notion that preformed soluble ICs can locate in the glomerular filter (18); and second, an affinity of DNA for the glomerular basement membrane (GBM) in vivo has been suggested (19-23), which could then initiate in situ IC formation. Extensive studies in animals on the kinetics and clearance of circulating free or immune complexed DNA (24-27) in regard to size and strandedness of DNA, however, revealed rapid nonrenal uptake and clearance. Prolonged DNA persistence is difficult to explain by accepted concepts; new proposals are needed (28). Contradictory findings on the occurrence of free or IC-bound DNA in sera from normal individuals and SLE patients have been reported (for review see reference 29). There are a number of technical problems involved here and it is now accepted that DNA-anti-DNA immune complexes represent only a minor part of the ICs found in lupus patients, and that increased levels ofcirculating DNA are found in a variety of conditions in which lysis ofcells occurs . Preliminary studies by Fournie (29) suggest that nucleosomes, which consist ofDNA This work was supported by the Deutsche Forschungsgemeinschaft, Ba 907/1-1.