A case of prolymphocytic leukaemia, showing several features not yet reported in this disease, is reported. The majority of lymphocytes in the peripheral blood and bone marrow had markers of both B- and T-lymphocytes. The simultaneous presence of receptors for sheep RBC and surface immunoglobulins on individual cells was demonstrated and the endogenous origin of these markers was established. The lymphocytes had some of the functional characteristics seen in chronic lymphocytic leukaemia (CCL). In vitro cell death in the presence of colchicine (colchicine ultrasensitivity) and polystyrene bead column retention were of the same order as seen in CLL. In contrast with the findings in CLL, these cells were markedly radioresistant in vitro. The dominant clinical features--anaemia and constitutional symptoms--appeared to be related to hypersplenism associated with massive splenomegaly. The relevance of these findings is discussed.

A set of conditions is defined for freeze‐storage of lymphocytes circulating in chronic lymphocytic leukaemia (CLL‐lymphocytes) and in healthy individuals (normal lymphocytes). Isolated cells are frozen in culture medium containing 15 % serum and 8.3 % (v/v) dimethyl sulphoxide (DMSO) at a post‐freezing cooling rate in the range 1.8‐–3.4° per min to −40° or below followed by immersion in liquid nitrogen, and thawed rapidly (ca. 400° per min) at 37°. This procedure induced consistently low mortalities (2–7%) in normal and CLL populations, uninfluenced by freeze‐storage lasting up to 57 weeks, and was accompanied by large‐scale destruction (67–100%, average 95 %) of residual isolated red cells. The lymphocytes classified as surviving cells by cytologic analysis could display partial loss of initial capacity for respiration but capacity for survival in short‐term culture was retained. Brief reference is made to unchanged ultrastructural appearance of surviving cells. No pronounced differences were observed in the capacity of normal populations to transform under the influence of phytohaemagglutinin (PHA) as a result of freezing and thawing, but tests for altered proliferative capacity of transformed cells were hampered by culture conditions proving sub‐optimal. Ultrasensitivity of CLL‐lymphocytes in vitro to cytocidal action of colchicine — a property currently utilized for measurement of abnormal cell content of CLL‐lymphocyte populations — was closely reproduced following freezing and thawing in experiments with 9 patients.

Circulating lymphocytes in chronic lymphocytic leukaemia (CLL) that die in vitro in 1 day of culture with 10‐7 M‐colchicine (0.04 μg 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.