Preferential idiotype-isotype associations in antibodies to dinitrophenyl antigens

Murine IgG antibodies to DNP-protein are predominantly IgG1 and IgG2 whereas those against DNP-Ficoll (DNP-F) are mainly IgG3. Isotype restriction in this and other systems may mean that certain heavy chain variable regions (VH) are preferentially associated with particular constant regions (CH) in the immune response. We studied idiotypes of several monoclonal antibodies to DNP in an effort to identify VH regions that may be restricted in this way. Two idiotypes, 7-17 and 8-11, identified on IgG3 hybridomas raised against DNP-Ficoll, were expressed prominently both in immune sera and by IgG3-secreting plaque-forming cells (PFC) against DNP-F. By contrast, these idiotypes were barely detectable in antisera to DNP-proteins and were not expressed by IgG1- or IgG2-secreting PFC. Thus, the 7-17, and 8-11 idiotypes may be restricted to IgG3 and to responses to T-independent DNP antigens. Conversely, the 460 idiotype was expressed prominently in antisera to DNP-proteins but only weakly in antisera to DNP-F. The 460 idiotype was found on IgG1 and IgG2 PFC but not on PFC secreting IgG3. These results suggest that in heterogeneous immune responses to a single antigenic determinant, certain VH regions may be preferentially associated with particular CH isotypes.