After immunization of mice with 2,4-dinitrophenyl-ovalbumin (DNP-OVA), it was shown previously that strains having Igh-Va genes and able to express light chains of the Vk1 group produce high levels of anti-DNP antibody bearing an idiotype (Id-460) associated with the combining site of the BALB/c DNP-binding myeloma protein MOPC 460. Expression of Id-460 in serum is transient; Id-460 levels peak early in the response and are regulated independently of total anti-DNP antibody. In this paper, the transient dominance of Id-460 expression has been confirmed at the cellular level by inhibition of splenic anti-DNP plaque-forming cells (PFC) with rabbit anti-Id-460 antiserum. Id-460+ PFC can account for 52-91% of anti-DNP PFC early after secondary challenge with DNP-OVA. Furthermore, Id-460 is represented at these high levels in IgM, IgG, and IgG1, and IgG2a, the three isotypes tested in the PFC assay, as well as in IgE, as tested by passive cutaneous anaphylaxis. Thus, there is no preferential association of Id-460 with a given isotype. We conclude from these studies that Id-460 is a dominant idiotype in the anti-DNP antibody response of BALB/c mice to DNP-OVA. This dominance is expressed transiently and is independent of isotype. A further conclusion from these studies is that regulation of isotype expression is independent of the regulation of idiotype expression in this system. We would suggest that regulation of Id-460 expression involves Ig-dependent helper T cells specific for Id-460 that induce Id-460+ B cells and also activate suppressor T cells, both events occurring via idiotype-anti-idiotype interactions.

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