In vitro studies with antisera against tumor cell protein fractions.

Antisera prepared in the rabbit against ribonucleoprotein fractions isolated from cells of the Ehrlich ascites carcinoma and the 6C3HED (#123) ascites tumor are capable of inhibiting the utilization of glycine-2-C14 by these cells in vitro . When cells of these tumors are incubated in vitro with the corresponding antiserum, loss of cell protein and ribonucleic acid results. Protein and ribonucleic acid remaining after a 90-minute incubation period may be reduced by as much as 50 per cent compared with the amounts of these components recoverable from cells incubated with normal rabbit serum. Rabbit antiserum prepared against a soluble protein fraction from Ehrlich cells is without effect on glycine-2-C14 utilization and on cell protein and ribonucleic acid. Several possible modes of action of the antisera are discussed.