Expansion of idiotype positive B cells in maternally idiotype suppressed mice.

The membrane expression of the J558 idiotype on B and T lymphocytes was studied in (A/J x BALB/c)F1 and (CAL.20 x BALB/c)F1 mice who were maternally suppressed for this idiotype. Animals suppressed in this fashion exhibit a chronic inability to synthesize J558 Id bearing antibodies in response to an antigenic challenge by alpha 1,3 linked dextran. However, by immunofluorescence, we observed that these maternally suppressed animals actually exhibited a considerable increase of B lymphocytes, which bear endogenously synthesized membrane immunoglobulin expressing the J558-IdI. Furthermore, a subset of T cells emerges that we have previously described as Lyt2.2+ cells exhibiting the J558-IdI determinant, which are capable of transferring the suppression to naïve recipients [1]. The goal of the experiments described in this communication was to thoroughly characterize those B cell clones that are expanded during idiotype suppression. Therefore, we immortalized these J558 Id+ B cells from idiotype suppressed mice as hybridomas. Four hybridomas secreting monoclonal antibodies bearing the J558 IdI but devoid of any specificity for alpha 1,3 linked dextran were obtained. It was established that these monoclonal antibodies bear the J558-Id by two criteria; namely, their direct binding to a panel of monoclonal anti-J558 IdI and a single anti-J558 IdX antibody, as well as by blocking the interaction of J558 with these antibodies. Notable was the fact that they all bore kappa light chains, even though in anti-dextran antibodies the expression of the lambda light chain is required for the expression of this idiotype. These results reaffirm the notion that idiotypic determinants are three dimensional structures which can be reconstructed by a variety of heavy and light chain sequences. Furthermore, an idiotope used in the regulation of an immune response (as our data implicate the J558 IdI is) is borne by antibodies displaying diverse specificities, which are coordinately regulated through this common idiotope.