Differential sensitivities of normal human and chronic lymphocytic leukemia lymphocytes to 1-methyl,3-isobutylxanthine and N6-2'-o-dibutyryl adenosine-3',5'-cyclic monophosphate.

Lymphocytes from patients with chronic lymphocytic leukemia (CLL) and from normal donors were cultured with 1-methyl,3-isobutyl xanthine (MIX) and N6-2'-o-dibutyryl adenosine-3',5'cyclic monophosphate (dbcAMP). MIX decreased the survival of CLL and normal lymphocytes during one day in culture; the magnitude of the MIX-sensitivity of the populations was similar to their colchicine-sensitivity, i.e. high for CLL and low for normal. dbcAMP increased cell death in one day cultures of lymphocytes from seven of fifteen CLL donors but inhibited the death of lymphocytes from the other eight donors. The protective effect of dbcAMP was not mimicked by adenosine monophosphate or adenosine diphosphate. The difference in sensitivity to dbcAMP provided a method for subdividing CLL lymphocyte populations which was examined for possible clinical significance.