Nonsequential expression of multiple immunoglobulin classes by isolated phosphorylcholine specific clones

Recent analyses show that the clones derived from the majority of phosphorylcholine (PC) specific B cells in nonimmune Balb/c mice express antibody identical in idiotype to the TEPC 15 myeloma protein; however, these monoclonal antibodies may be heterogeneous in their immunoglobulin heavy chain class. Thus, in vitro stimulation of isolated B cells with a PC tripeptide spacer hemocyanin antigen, allowing maximal carrier recognition in carrier primed splenic fragment cultures, results in the synthesis of IgM, IgG1, and IgA immunoglobulins. Idiotype and isoelectric focusing analyses confirmed that the TEPC 15 idiotypic determinant can be shared by 2 or more heavy chain classes, produced by the clonal progeny of a single stimulated B cell. When monoclonal antibody of the TEPC 15 idiotype is examined with time after antigenic stimulation, it is observed that the onset of the expression of different immunoglobulin classes is variable in that any heavy chain class can appear singly, or in combination with the others. In this regard, no evidence was found on an immunoglobulin weight basis for a sequential shift from IgM to IgG or IgA by stimulated clones in such a carrier primed environment.