Comparative Studies on the in vitro Uptake of ³H‐Cytidine and ³H‐Uridine by Normal and Leukaemic Lymphocytes

Abstract

In vitro labelling of lymphocytes by RNA precursors is a useful tool to study the characteristics of normal and leukaemic cell populations. Basic conditions have been studied for in vitro labelling and indicated a desired level of cell concentration (2 × 104 to 2 × 105) and temperature (37° C). Normal leukocytes showed a fairly constant behaviour with respect to total uptake of radioactivity, incorporation into intracellular fractions and the ratio of 3H‐cytidine to 3H‐uridine incorporation (average ratio 10 ± 1). In contrast, the blood lymphocytes of patients with chronic lymphocytic leukaemia (CLL) exhibited a great variation in the parameters studied, ranging from below normal to several times normal values. This broad spectrum of in vitro characteristics has to be taken into consideration when populations of CLL lymphocytes are compared to normal lymphocytes and to those of other lymphatic disorders.