Spleen extracts and sera from C57BL/10 mice bearing a reticulum cell lymphoma were found to contain elevated levels of protein when compared with normal mouse levels. Immunodiffusion, immunoelectrophoresis, gel filtration, and density gradient ultracentrifugation studies indicated the protein to be an IgM macroglobulin. The increased macroglobulin level was correlated, in part, with the growth of the tumor, reaching a peak 2.5 times greater than that for the control mice. The peak was reached 6 days after tumor transplant and remained at this level until the animals died from the tumor, approximately 14 days after the transplant.

Purified IgM from lymphomatous and normal mice were indistinguishable immunologically as antigens. Peptide map analyses of isolated light chains from partially reduced and alkylated IgM suggested that the IgM light chains from tumor-bearing mice were more heterogeneous than myeloma light chains; i.e., the elevated IgM was not a myeloma.

A protein was found in the urine of tumorous mice that migrated electrophoretically in the globulin region. Immunological studies and peptide map analyses revealed the protein to be albumin-like. The significance or relationship of the electrophoretically altered albumin to the elevated IgM levels or to the growth of the lymphoma was not determined.

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This research was supported by research funds obtained from the University of Texas at Austin, Austin, Texas 78712.

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