The cytotoxic action of immune gamma globulin and complement on Krebs ascites tumor cells. II. Chemical studies.

The in vitro exposure of Krebs ascites tumor cells to the action of rabbit immune gamma globulin alone does not result in any changes in the cell concentration of amino acids, ribonucleotides, RNA, DNA, or protein, nor in the rate of entry of potassium into the cell. The exposure of the cells to antibody + complement results in the following changes within a few minutes:- (a) Loss of about two-thirds of the free amino acids and ribonucleotides. (b) Loss of about 90 per cent of the intracellular potassium. (c) Loss of about three-quarters of the cell RNA to the medium, part appearing as TCA-soluble and the rest as TCA-insoluble products. There were no changes detectable in DNA. (d) A small increase in total free amino acid of the cell suspension. (e) Loss of from 30 to 60 per cent of the cell protein. The loss of these substances is believed to occur through a cell membrane which is still intact, as judged by phase and electron microscopy, and still able to discriminate to a small degree against passage of larger molecules.