Immunochemical, Structural and Translocating Properties of Anti-DNA Antibodies from (NZB×NZW)F1 Mice

Abstract Many monoclonal antibodies (mAb) derived from the spleens of (NZB×NZW)F1 mice react strongly with dsDNA and also other self antigens, although more weakly. When added to cell cultures, these polyreactive anti-DNA mAb penetrate into various cell types and accumulate in the nucleus within a few hours. Almost all anti-DNA mAb bind to cell membrane antigens but the extent of their binding does not directly correspond to their penetration capabilities. Sequence analysis of anti-DNA mAb indicated the use of various germ-line V H families. The complementary-determining regions (CDR) 3 differ but they all contain a relatively high number of tyrosines and positively charged amino acids (lysine and arginine). Haptens (biotin, fluor-escein, oligonucleotides) and macromolecules (peroxidase, IgG) covalently coupled to the mAb or their F(ab′)2 and Fab fragments were translocated through the cytoplasm and into the cell nucleus. Furthermore, 61% of peripheral blood lymphocytes were labelled when mice were injected with fluorescein-labelled mAb. Peptides corresponding to CDR2, CDR3 and CDR2 linked to CDR3 (CDR2–3) of several penetrating mAb were prepared and their intracellular translocating capacity was assessed. The CDR2–3 peptide, but not the individual peptides, was able to penetrate cells and could be used as a vector to transport macromolecules. Although all CDR2–3 reacted with dsDNA and other self antigens, each one exhibited a distinct polyreactivity profile.