Restoration of a normal level of immunoglobulin production in a hybridoma cell line following modification of the chromosomal immunoglobulin mu gene by gene replacement.

In the present investigation, we have measured the levels of IgM mRNA and protein in recombinant cell lines in which the chromosomal immunoglobulin mu gene has been modified by gene replacement (gene conversion or double reciprocal recombination) or vector integration (single reciprocal recombination) events. Our studies reveal that chromosomal immunoglobulin mu genes modified by gene replacement are expressed at wild-type levels whereas those modified by vector integration have lower levels of immunoglobulin mu gene expression. These results suggest that gene replacement may a preferred method for the construction of hybridoma and myeloma cell lines producing optimized immunoglobulins and for studies of immunoglobulin gene function.