THE SENSITIVITY OF CHRONIC LYMPHOCYTIC-LEUKEMIA LYMPHOCYTES TO IRRADIATION IN-VITRO

The inhibition of [H-3]-thymidine incorporation into the DNA of mitoge n-stimulated chronic lymphocytic leukaemia lymphocytes by chlorambucil or gamma-irradiation in vitro was measured in a series of patients, s ome of whom were untreated, some treated and some who were showing res istance to first-line or second-line treatment. There was evidence of resistance to irradiation developing in parallel with that to chloramb ucil. The resistance to chlorambucil in chronic lymphocytic leukaemia (CLL) is not necessarily due to altered drug transport or metabolism b ut to a more fundamental process affecting DNA damage.