Anemia-inducing substance from plasma of patients with advanced malignant neoplasms.

Patients with advanced malignant neoplasms develop anemia and immunosuppression. During an attempt to identify the causes, we have found that plasma from such patients makes RBCs more fragile in hypotonic buffer, according to results obtained with a coil planet centrifuge. Plasma from these patients suppresses mitogen-stimulated lymphocyte proliferation. In this study, we identified the substance with these effects as a protein. During two-dimensional gel electrophoresis, two isomers with M(r) 50,000 and slightly different isoelectric points near 6.0 were found. Cell fractionation showed that these proteins were in both the cytosol and the nuclear fraction of cells in neoplasms. Another protein with the same antigenicity and a M(r) 100,000 found in the nuclear fraction of cells in neoplasms.