IgM-Induced Specific Antibody Responses: Direct Correlation between Responsiveness and Natural or Induced Recurrence of the Idiotype

The idiotype (Id) expressed on antibodies of the trinitrophenol (TNP)-spccific BALB/c hybridoma TNP.11 is defined as a 'nonrecurrent' or private Id in BALB/c mice, whereas the analysis of splenic plaque-forming cells (PFC) and circulating antibody in DBA/2 mice immunized with TNP antigens revealed that TNP.11 is a 'recurrent' Id in this strain. TNP.11 antibodies were characterized by their ability to induce an antigen-independent anti-TNP response in these two strains. Whereas this antibody was negative in BALB/c mice 18], a clearcut increase in splenic anti-TNP PFC, preferentially expressing the TNP.11 Id, was observed in DBA/2 mice. This correlation between Id recurrency and ability to induce antigen-independent responses was further probed in BALB/c mice repeatedly immunized with anti-TNP.11 Id antibodies (Ab3). Such BALB/c mice express the TNP.11 Id in detactable amounts even without antigen challenge and respond with increased numbers of splenic anti-TNP PFC to the injection of low amounts of TNP.11 antibody. These findings suggest that the ability of an antibody to induce antigen-independent PFC responses is associated with the'recurrency', either natural or induced, of the antibody Id.