Deoxycytidylate deaminase activity in lymphoproliferative disorders

The activity of dCMPase has been measured in cell extracts from human lymphoproliferative disorders. The highest levels occurred in T helper-CLL and Thy-ALL, but high levels were also found in C-ALL, NPDLL transforming to DHL, DPDLL and DHL. A range of enzyme activities was found in the majority of types examined, with the widest range encountered in ALL, NPDLL and DHL. In DWDLL, a narrow range of dCMPase activities was found, with enzyme levels in the control range or moderately increased. Similarly, B-CLL exhibited a narrow range of enzyme activities, within that of the controls. The highest enzyme activity in HD was found in the highly malignant type — lymphocyte depleted HD. Statistically significant differences were found between the distribution of dCMPase activities in ALL and the chronic leukemias; and between favorable histologic types of non Hodgkin's lymphomas and the unfavorable DHL type. These data suggest that dCMPase activity is a marker of the clinical aggression of human lymphoid malignancies. Moreover, the marked variation in enzyme activity in each type of lymphoid malignancy suggests that this also applies to individual tumors as well. In view of the important role of dCMPase in pyrimidine metabolism and the profile of enzyme activities in leukemia and lymphoma, it is suggested that an inhibitor of dCMPase could be of clinical value in lymphoid malignancy.