TUMOR REGRESSION INDUCED IN MICE BY PARTIALLY PURIFIED LYMPHOKINE FRACTIONS *

Over the past six years our studies have involved the use of cell-free supernatants derived from long term cultures of human and mouse lymphoblast cell The properties of lymphocyte mediators (lymphokines) have been extensively reviewed 4 9 and a recent workshop summary on this subject covers basic and clinical aspects.'j Human peripheral blood lymphocytes have proved to be rich sources of lymphokine-containing supernatants and have been used for most studies on in vitro lymphokine properties. We have used lymphoblast cell lines as sources of starting material rather than antigen or lectin-stimulated peripheral blood lymphocytes. The purpose has been solely to obtain large quantities of starting material for use in animal studies, preclinical and clinical toxicity studies, standardizing tests for biological properties, and biochemical characterization. In all of these studies, large quantities of starting materials from the same lot are required in order to compare effects on a regular basis. In spite of using the same cell line, variations in the biological properties of supernatants from lot to lot have provided some difficulties in the preparation and purification of materials, as well as biological assay. Early laboratory and clinical studies have been published and I report here our more recent mouse tumor assay experiments and some of the B-cell stimulation studies performed by Drs. Butler and Specter in Dr. Herman Friedman's laboratory. Methodology for the establishment and maintenance of human lymphoid cell lines has been described,' as well as the preparation of supernatant lympho-