[Resistance of ascitic fluid immunosuppressive factor DNA to pancreatic deoxyribonuclease]

It was found that incubation of Ehrlich tumour ascitic fluid with pancreatic DNAse does not result in a destruction of 5S DNA in the immunodepressive factor. After phenol deproteination of the ascitic fluid the resistance of this nucleic factor to DNAse is lost. It is possible that the native nucleic factor is represented by DNP and contains a protein component. During polyacrylamide gel electrophoresis the mobility of the nucleic factor labelled with [3H]-thymidine and isolated after chromatography on hydroxyapatite is found to be nearly the same as that for transferine.