IMMUNOGLOBULIN BIOSYNTHESIS .I. A MYELOMA VARIANT SECRETING LIGHT CHAIN ONLY

A mutant mouse myeloma cell line was derived from ADJPC5, which secretes an IgG2a immunoglobulin. The variant had lost the ability to synthesize immunoglobulin, but continued to secrete light chain. This light chain, and the light chain from ADJPC5 immunoglobulin, were indistinguishable as defined by peptide mapping of the secreted serum, and urinary proteins. Karyotype analysis showed that the mutant was derived from one of the 14 stem-lines observed in the wildtype myeloma. There was no detectable internal immunoglobulin in the variant, ruling out a block in secretion. It was also shown that the differential rate of light chain secretion was identical in ADJPC5 and its derivative. © 1968.