Effect of native and modified bull seminal ribonuclease on tumour and testicular cells and phytohaemagglutinin-stimulated pig lymphocytes.

The carboxymethylated, oxidized and reduced forms of AS RNase inhibited transplantability and DNA synthesis of tumour cells BP-8 and EL-4 incubated in vitro. With tumour cells EL-4 the results under in vitro conditions did not not correspond to those obtained under the conditions in vivo. The survival of mice given injections of EL-4 cells and of the native and carboxymethylated AS RNase was only slightly prolonged. Mice that received intra-abdominally BP-8 cells and both carboxymethylated and oxidized and reduced forms of AS RNase survived two or three times longer than the controls. Succinylation and maleylation of AS RNase eliminated any antitumoral effect. Aspermatogenic activity of AS RNase was abolished by any modification of the molecule which had substantially reduced, or removed, the RNase activity. Neither native nor modified forms of AS RNase had an inhibitory effect on unstimulated pig lymphocytes. The DNA synthesis of PHA-stimulated lymphocytes was inhibited by the native and carboxymethylated AS RNase only. Bovine pancreatic A RNase had any inhibitory effect on neither tumour nor testicular cells.