The homogeneous-gamma-G-immunoglobulin produced by mouse plasmacytoma 5563 and its subsequent heterogeneity in serum.

The mouse plasma cell tumour 5563 has been shown to synthesize and secrete a single molecular species of gammaG-immunoglobulin, which was identified by labelling with (14)C-labelled amino acids. The heterogeneity of G-myeloma globulin as it is found in serum of tumour-bearing mice is due to subsequent changes in the charge properties of the newly secreted molecules. These changes have been reproduced in vitro. On incubation with sterile serum, the newly formed radioactive myeloma protein changed its chromatographic and electrophoretic properties to coincide with those of myeloma protein isolated from serum. Incubation of purified myeloma protein band a, under a variety of conditions, led to the characteristic pattern of serum myeloma protein showing multiple electrophoretic bands. The chemical nature of the molecular changes is not yet known. It is suggested that seruminduced changes could contribute to the electrophoretic heterogeneity of specific antibodies within the gammaG-class of immunoglobulins. This demonstration of the production of a single molecular species of immunoglobulin by a plasma cell tumour provides support for the concept of ;one-cell-one antibody'.