Killing and Characterizing Action of Colchicine in vitro on Lymphocytes of Chronic Lymphocytic Leukaemia

Abstract

Circulating lymphocytes in chronic lymphocytic leukaemia (CLL) that die in vitro in 1 day of culture with 10 ‐7 M ‐colchicine (0.04 μ g per ml) have been classed as abnormal cells. Most of the increase in peripheral count in 30 patients so far tested (treated or untreated) is due to cells of this type. A colchicine concentration 100 , 000 times greater (10 ‐2 M ) kills peripheral populations from healthy individuals in one day. Use of nuclear pyknosis as the index of death has been validated by metabolic and ultrastructural examination of pyknotic lymphocytes. Kinetic studies suggest that initiation of pyknotic degeneration of an abnormal population is achieved at a colchicine concentration of 10 ‐7 M in ca . 10 hrs — or at higher concentrations in shorter times inversely related to concentration — after attainment of a seemingly critical level of colchicine binding by the population. From comparative cytocidal tests with several structural analogues, and with vinblastine, it is suggested that mode of cytocidal action of colchicine may have a biophysical basis like its antimitotic action involving binding in lymphocytes to micro‐tubular elements. One such analogue, trimethylcolchicinic acid methyl ether (NSC 36354) may be of therapeutic value in treatment of CLL.