Increasing human serum ribonuclease activity is a concomitant phenomenon of ovarian carcinoma.

The levels of total human serum RNAase activity (HSRA) from 24 patients with ovarian cancer have been followed up for a period of over 5 months. The determinations of HSRA were carried out according to our assay system described earlier. Two representative patterns of the HSRA are presented, one from a patient with an ascertained remission of an ovarian carcinoma. Increasing HSRA values are concomitant with tumor progression while in remission the HSRA remains at normal rates. We have reported earlier that optimum HSRA depends on physiological concentrations of NaCl in the reaction mixture. However, NaCl can be replaced by KCl without a loss of activity. No correlation was detectable between increased HSRA and an excessive electrolyte content in serum. The mixtures of sera with various RNAase activities showed linear additivity. These findings suggest that an increased concentration of the RNAases normally present in human serum and/or additional RNAases are responsible for the increase of the HSRA.