Analysis of autoantibody production and regulation system using monoclonal anti-DNA antibodies

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Using the somatic cell hybridization technique, we have established 14 hybridomas which produces antibodies to DNA. On the basis of all our data, antibdies reacting with DNA can be basically classified into two groups. One includes antibodies which react exclusively with ssDNA and which have a restricted specificity to DNA base. The other includes antibodies which are serologically polymorphic in that they can react with a variety of polynucleotides including ssDNA, dsDNA and synthetic RNA.We selected three anti-ssDNA monoclonal antibodies specific for poly(dG) and attempted to further elucidate the precise specificity of antigenic determinants of nucleic acids using a hapten inhibition assay. We obtained the results that the anti-ssDNA monoclonal antibody recognized the primary base sequences rather than the tertiary structure of nucleic acids, that the poly(dG) specific hybridoma antibodies had specificity restricted to the base and sugar part of nucleic acids and that the phosphate … More part of DNA may contribute little to the epitope formation of ssDNA. Our data also suggest the mnimal antigenic size of ssDNA corresponds to the tetra- or pentanucleotide.We observed that polyspecific anti-DNA antibodies (anti-ss/dsDNA) could cross-react with cardiolipn, the chemical structure of which is similar to that of polynucleotide backbone. A biological false positive serological test for syphilis (BFP-STS) is a well recognized characteristic of patients with SLE and cardiolipin is a major antigen in the STS. Therefore, it iwas assumed that the BFP reactors in SLE sera were due to the antibodies which had the ability to react with ssDNA, dsDNA and cardiolipin. However, hybridoma capable of binding to both DNA and the VDRL antigen were not detectable.All these findings taken together lead the proposal that anti-DNA antibodies which react with common antigenic determinants on the phosphate-sugar backbone of nucleic acid can bind to the cardiolipn, as there is a structural similarity in the nucleic acid backbone, but differ from the BFP reactors. Less