Purification of placental anemia inducing factor (PAIF) and its clinical application by radioimmunoassay.

Human Placental Anemia Inducing Factor (PAIF) was purified from crude placental preparation called P- 62, which had common biological and immunological natures with the same preparation from gastric juice, gastric tissues, serum and urine of patients with malignant neoplasma, especially gastric cancer. The obtained PAIF was homogeneous on polyacrylamide gel electrophoresis and gave a specific band in the region of gamma-A and/or gamma-M globulin on immunoelectrophoresis. The purified PAIF induced anemia in rabbits by intravenous administration at a dose of 2.7 micrograms/Kg of body weight. No cross antigenicity of PAIF was observed with alpha-Fetoprotein. HBs antigen and CEA. Serum AIF of patients was measured using PAIF as a standard by radioimmunoassay. AIF levels in sera of patients with malignant neoplasma were significant high compared with those of control groups.