Isolation and Characterization of Canine Venereal Tumor-associated Inhibitory and Blocking Factors

Robert B. Epstein, William E. Beschorner, Allan D. Hess, Samuel T. Nerenberg

Research output: Contribution to journalArticle

Abstract

Spontaneous regression of the canine venereal tumor is associated with the production of a serum factor which inhibits in vitro tumor colony-forming units in agar. Logarithmic or persistent tumor growth, on the other hand, is characterized by a serum factor which protects cells against in vitro inhibition (blocking factor). These factors have been characterized by immunochemical methods. Whole regressor and blocking sera were fractionated by Sephadex G-200 filtration and immunoabsorption with rabbit antiserum specific for canine immunoglobulin G2a. Fractions were characterized by immunoelectrophoresis, radial immunodiffusion, and disc gel electrophoresis. In vitro inhibitory and blocking activity of the whole serum was accounted for by the purified immunoglobulin G2a. Blocking activity was also found in protein eluted from logarithmically growing tumors. Preparative polyacrylamide electrophoresis revealed five major fractions with blocking activity only in the immunoglobulin G fraction. Tumor eluates and immunoglobulin G isolated from serially removed tumors demonstrated relative inhibitory and blocking activities that correlated with the clinical course of the tumor. Using ultrafiltration and sodium dodecyl sulfate electrophoresis of tumor-associated immunoglobulin G at low pH, it was not possible to identify an antigen complexed to the blocking antibody.

Original languageEnglish (US)
Pages (from-to)3920-3927
Number of pages8
JournalCancer Research
Volume39
Issue number10
StatePublished - Oct 1 1979

    Fingerprint

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

Cite this

Epstein, R. B., Beschorner, W. E., Hess, A. D., & Nerenberg, S. T. (1979). Isolation and Characterization of Canine Venereal Tumor-associated Inhibitory and Blocking Factors. Cancer Research, 39(10), 3920-3927.