Cellular requirements for anti-DNA production induced in mice by immunization with bacterial DNA

To further define DNA immunization as a model for anti-DNA production, we investigated the cellular requirements for this response in mice immunized with single-stranded DNA from E. coli. The anti-DNA responses of genetically immune-deficient mice and congenic controls were measured by ELISA after immunization with E. coli DNA as complexes with methylated bovine serum albumin in complete Freund's adjuvant. T cell-deficient BALB/c-nu/nu mice failed to produce IgG anti-DNA by this protocol despite high backgrounds of IgM anti-DNA. In contrast, CBA/N mice expressing the xid defect displayed IgG anti-DNA responses comparable to those of CBA/J mice despite a reduced IgM response; the specificity of CBA/N and CBA/J anti-DNA antibodies was similar as determined by binding to synthetic DNA and RNA antigens. These results suggest that the anti-DNA response stimulated by DNA immunization is dependent on T cells but not the B cell population affected by xid. The intact IgG response of immunized xid mice differs from that of lupus mice bearing xid where this gene defect leads to significant reduction of spontaneous anti-DNA production.