A simple in-vitro test for assessing the sensitivity of lymphocytes to chlorambucil

The sensitivity of lymphocytes to chlorambucil has been assessed by a simple in-vitro test which has been applied to the cells of normal controls and of patients with chronic lymphocytic leukaemia. The degree of sensitivity varied amongst the normal controls and in-vitro resistance of the lymphocytes in the patients was sometimes found in the absence of in-vivo experience of the drug. Resistance in-vitro tended to be associated with very high total peripheral blood lymphocyte counts but not with the age of the patient. Where the information was available the in-vitro sensitivity test agreed with the results of biochemical estimations of drug resistance and with the clinical responses to the drug. It is suggested that this test may have applications in patient management.