Expression of a recombinant murine IgE in transfected myeloma cells

We constructed a recombinant gene encoding an immunologlobulin (Ig) heavy chain consisting of the variable region from the phosphorylcholine (PC)-specific secreting myeloma MOPC167 and the ε constant region from SJL mice. This gene, cloned into the shuttle vector pSV2gpt, was transfected into J558L myeloma cells, and stable transformants that expressed the ε gene were cloned. The IgE heavy chain in these transformants is associated with the endogenous λ light chain and is secreted as an intact IgE molecule. However, the secreted IgE does not bind to PC conjugated to bovine serum albumin (PC-BSA). The MOPC167 κ chain gene was cloned into the shuttle vector pSV2neo and was transfected into the ε heavy-chain transformant. Stable transformants were cloned that expressed both the ε heavy chain and the κ light chain. IgE secreted from such a transformant was shown to bind to PC-BSA. Both types of secreted recombinant IgE bound to rat basophilic leukemia (RBL) cells, but only the IgE produced by the cell line transformed with the MOPC167 κ gene could be cross-linked with PC-BSA to cause serotonin release.