Abstract
In the previous paper, it was shown that if Ehrlich ascites tumor cells are brought into contact with the normal human serum, typical cytolysis (oncolysis) results. For this oncolysis three factors (heat-stable and heat-labile factors and Mg2+) are necessary. In this paper, the nature of the heat-labile factor was discussed with special reference to its difference from complement. Following conclusions are drawn.
1) On heating, treating with zymosan, with specific antigen-antibody complexes, or with ammonium chloride, the activity of heat-labile factor in the oncolysis and that of the hemolytic complement disappear simultaneously.
2) In oncolysis, too, consumption of complement, especially that of the endpiece, and the third and fourth components of complement can be demonstrated.
3) Even in the sera, in which the heat-labile factor is completely consumed by oncolysis or inactivated by dialysis against distilled water, the hemolytic activity is still preserved.
4) For oncolysis, besides the four components of complement, another substance is necessary. This substance is heat-labile, inactivated by dialysis against distilled water, and is contained in the serum fraction precipitated by ammonium sulfate at the concentration of 1.39-2.0M.
5) Properdin has no relation to oncolysis in the present sense.
