Distinctive Myeloma Globulins Associated with a New Plasma Cell Neoplasm of Strain C₃H Mice

A transmissible plasma-cell neoplasm (5647) accompanied by marked serum protein changes has been described in the mouse. The principal characteristics of this neoplasm and the associated serum protein changes have remained unchanged during two years of observation.

The transplanted neoplasm usually remains confined to the site of implantation. Osteolytic lesions and abnormal cells in the peripheral blood were not seen.

Morphologically the neoplastic cells retain many characteristics of normal plasma-cells, with clumping of the nuclear chromatin, an eccentric nucleus and a clear zone in the basophilic cytoplasm.

Serum electrophoretic analyses revealed a markedly abnormal serum protein pattern. The total serum protein was increased by two to three grams per cent in mice bearing 5647 neoplasms weighing 6 grams or more. Increased amounts of proteins with beta globulin and fast gamma globulin electrophoretic mobility were the most striking electrophoretic findings. These components comprised as much as 35 per cent of the serum proteins in animals with large neoplasms.

Serum ultracentrifugal analyses also demonstrated a markedly abnormal distribution of the serum proteins. Normal mouse serum contains components with sedimentation coefficients (S_20,W) of 4, 6.5 and 16 S. Serum of mice bearing neoplasm 5647 contained, in addition to the normal components, proteins with sedimentation coefficients of 9, 11 and 13 S. These serum components, accounting for as much as 20 per cent of the total protein, have been found only with neoplasm 5647.

The quantity of the abnormal serum components seen on electrophoretic and ultracentrifugal analyses was found to increase as the tumor weight increased.

Bence Jones protein was not found in the urine of mice bearing the 5647 neoplasm.

Neoplasm 5647 was found to differ significantly in biologic behavior and in the associated serum protein changes from two other transmissible plasma-cell neoplasms of the mouse (5563 and 70429) which have been under observation in these laboratories.

The mouse plasma-cell neoplasm 5647 resembles in several characteristics the malignant plasmacytomas in man having associated myeloma proteins of beta globulin electrophoretic mobility.