Both natural and induced murine anti-TNP antibodies possess anti-DNA activity.

Sera of BALB/c mice immunized with either trinitrophenyl (TNP) coupled to bovine serum albumin (TNP/BSA) and Freund's adjuvant or TNP/BSA and TNP coupled to mouse serum albumin (TNP/MSA) without adjuvant were tested for antibody activity against a panel of antigens: TNP/BSA, DNA, actin, myosin, tubulin and transferrin. Anti-DNA antibody activity in the serum increased significantly in immunized mice; this activity followed the increase in the anti-TNP titres. Sera from MRL/lpr/lpr autoimmune mice were also tested for antibody activity against a panel of antigens. Again, it was found that the level of the anti-TNP antibodies followed the level of anti-DNA antibodies. Purified antibodies isolated from both immunized BALB/c and MRL/lpr/lpr mice on a dinitrophenol(DNP)-lysine immunoadsorbent shared antibody activity against both TNP and DNA. The results obtained suggest that a single region in the antibody binding site is responsible for both anti-DNA and anti-TNP activities, that TNP-like groups may represent a "public epitope" carried by various antigens and that antibodies obtained after experimental immunization and antibodies appearing in autoimmunopathological situations apparently possess similar specificities.