Antitumor factors of regional lymph node cells in the transplantation of Ehrlich ascites tumor cells. II. Properties of antitumor factors

With the purpose to elucidate further the properties of the supernatant F4 obtained by centrifugation at 100, 000 g from the regional lymph node cells of the Cb mice sensitized with EHRLICH ascites tumor cells, the supernatant (cf. Report 13) was subjected to the following treatments:. The supernatant (F4) was first diluted variously with Hanks solution. 2. F4 was passed through Seitz filter. 3. Heated at 56°C for 30 minutes. 4. It was frozen and thawed. 5. Treated with O. 01 96 trypsin solution. Each of F4 frations so treated was used in the tissue culture of JTC-II cells (derived from EHRLICH cancer cells) as target cells. As a result we found that the antitumor factor passes th rough Seitz filter, and it loses its antitumor activity by 4-fold dilution or over. Likewise F4 loses its activity by freezing-thawing treatment as well as by trypsin treatment, while by heat treatment at 56°C for 30 minutes, it still retains its activity. From these finding, it is assumed that the antitumor factor contained in F4, fraction is not serum antibody but is a protein associated with the cell membrane.