Serum antibody-binding antibodies produced during a primary antibody response.

By using a solid phase radioimmunoassay we have demonstrated that immunization with either polyinosinic.polycytidylic acid (rl.rC) or TNP-Ficoll (both Tl-2 antigens) leads to the late production (day 10 to 15) of an IgG anti-antibody with specificity for the early (day 4 to 5) IgM produced in response to primary immunization. Adsorption of late sera with antigen removes anti-rl.rC or anti-TNP but does not remove anti-antibody. These results show that specific anti-antibody is found in serum during a primary immune response, and its appearance is coincident with a fall in serum anti-antigen. This suggests a possible role of autologous anti-antibody in regulation of a primary immune response.