Immunity to p53 induced by an idiotypic network of anti-p53 antibodies: generation of sequence-specific anti-DNA antibodies and protection from tumor metastasis.

The general overexpression of p53 by different types of tumor cells suggests that p53 immunity might be generally useful for tumor immunotherapy. We describe here the induction of immunity to p53 and resistance to tumor metastasis using an idiotypic network. Mice were immunized with domain-specific anti-p53 monoclonal antibodies (Ab1): PAb-248 directed to the N-terminus; PAb-246 directed to the specific DNA-binding region; or PAb-240 directed to a mutant p53 that does not bind specific DNA. Immunized mice responded by making anti-idiotypic antibodies (Ab2) specific for the Ab1 inducer. Ab1 PAb-246 induced Ab2 that, like p53 itself, could bind the specific DNA oligonucleotide sequence of the p53 responsive element. Mice immunized with Ab1 PAb-240 or PAb-246 spontaneously made Ab3 anti-p53 antibodies that reflected the specificity of their Ab1 inducers: Ab1 PAb-246 induced Ab3 specific for wild-type p53; PAb-240 induced Ab3 specific for mutant p53. Ab1 PAb-248 induced only Ab2. The spontaneously arising Ab3 were of T cell-dependent IgG isotypes. Peptides from the complementarity determining regions of the Ab1 antibodies PAb-240 and PAb-246 could also induce Ab3 anti-p53. Finally, mice that produced Ab3 anti-p53 acquired resistance to tumor metastases. Therefore, an anti-idiotypic network built around certain domains of p53 seems to be programmed within the immune system, specific Ab2 antibodies can mimic the DNA binding domain of p53, and Ab3 network immunity to p53 can be associated with resistance to tumor cells.

Systemic lupus erythematosus in mice, spontaneous and induced, is associated with autoimmunity to the C-terminal domain of p53 that recognizes damaged DNA.

The tumor suppressor molecule p53 features a regulatory domain at the C terminus that recognizes damaged DNA. Since damaged DNA might be involved in activating anti-DNA autoantibodies, we tested whether autoimmunity to the C terminus of p53 might mark murine systemic lupus erythematosus (SLE). We now report that MRL / MpJ-Fas(lpr) mice, which spontaneously develop SLE, produce antibodies both to the C terminus of p53 and to a monoclonal antibody (PAb-421) that binds the p53 C terminus. Anti-idiotypic antibodies to PAb-421 (sampled as monoclonal antibodies) could also bind DNA. Thus, the PAb-421 antibody mimics DNA, and the anti-idiotypic antibody to PAb-421 mimics the p53 DNA-binding site. This mimicry was functional; immunization of BALB / c mice to PAb-421 induced anti-DNA antibodies and antibodies to the C terminus of p53, and most of the mice developed an SLE-like disease. Immunization of C57BL / 6 mice to PAb-421 induced antibodies to p53, but not to its C-terminal domain. The C57BL / 6 mice also did not develop anti-DNA antibodies or the SLE-like disease. Thus, network autoimmunity to the domain of p53 that recognizes damaged DNA can be a pathogenic feature in SLE in genetically susceptible strains of mice.