Isolation of rat immunoglobulin class switch variants of rat‐mouse hybridomas by enzyme‐linked immunosorbent assay and sequential sublining

The use of sequential sublining in combination with highly specific and sensitive enzyme‐linked immunosorbent assays for the isolation of spontaneous rat Ig heavy chain class switch variants is described. These methods allowed us to isolate switch variants from mouse‐rat hybridoma lines secreting monoclonal rat antibodies. Switch variants from IgM to IgG2a, from IgG2a or IgG2b to IgE and from IgE to IgA were obtained. Members of the BA1.2 family, which consists of IgG2b, IgE and IgA antibodies are shown to exhibit identical rhamnose‐inhibitable binding to the O18A antigen of Escherichia coli and to the paratope‐associated anti‐idiotypic antibody BA114.